This file is indexed.

/usr/lib/pypy/dist-packages/wand/image.py is in pypy-wand 0.3.5-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
""":mod:`wand.image` --- Image objects
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Opens and manipulates images. Image objects can be used in :keyword:`with`
statement, and these resources will be automatically managed (even if any
error happened)::

    with Image(filename='pikachu.png') as i:
        print('width =', i.width)
        print('height =', i.height)

"""
import collections
import ctypes
import functools
import numbers
import weakref

from . import compat
from .api import MagickPixelPacket, libc, libmagick, library
from .color import Color
from .compat import (binary, binary_type, encode_filename, file_types,
                     string_type, text, xrange)
from .exceptions import WandException
from .resource import DestroyedResourceError, Resource
from .font import Font


__all__ = ('ALPHA_CHANNEL_TYPES', 'CHANNELS', 'COLORSPACE_TYPES',
           'COMPOSITE_OPERATORS', 'EVALUATE_OPS', 'FILTER_TYPES',
           'GRAVITY_TYPES', 'IMAGE_TYPES', 'ORIENTATION_TYPES', 'UNIT_TYPES',
           'BaseImage', 'ChannelDepthDict', 'ChannelImageDict',
           'ClosedImageError', 'HistogramDict', 'Image', 'ImageProperty',
           'Iterator', 'Metadata', 'OptionDict', 'manipulative')


#: (:class:`tuple`) The list of filter types.
#:
#: - ``'undefined'``
#: - ``'point'``
#: - ``'box'``
#: - ``'triangle'``
#: - ``'hermite'``
#: - ``'hanning'``
#: - ``'hamming'``
#: - ``'blackman'``
#: - ``'gaussian'``
#: - ``'quadratic'``
#: - ``'cubic'``
#: - ``'catrom'``
#: - ``'mitchell'``
#: - ``'jinc'``
#: - ``'sinc'``
#: - ``'sincfast'``
#: - ``'kaiser'``
#: - ``'welsh'``
#: - ``'parzen'``
#: - ``'bohman'``
#: - ``'bartlett'``
#: - ``'lagrange'``
#: - ``'lanczos'``
#: - ``'lanczossharp'``
#: - ``'lanczos2'``
#: - ``'lanczos2sharp'``
#: - ``'robidoux'``
#: - ``'robidouxsharp'``
#: - ``'cosine'``
#: - ``'spline'``
#: - ``'sentinel'``
#:
#: .. seealso::
#:
#:    `ImageMagick Resize Filters`__
#:       Demonstrates the results of resampling images using the various
#:       resize filters and blur settings available in ImageMagick.
#:
#:    __ http://www.imagemagick.org/Usage/resize/
FILTER_TYPES = ('undefined', 'point', 'box', 'triangle', 'hermite', 'hanning',
                'hamming', 'blackman', 'gaussian', 'quadratic', 'cubic',
                'catrom', 'mitchell', 'jinc', 'sinc', 'sincfast', 'kaiser',
                'welsh', 'parzen', 'bohman', 'bartlett', 'lagrange', 'lanczos',
                'lanczossharp', 'lanczos2', 'lanczos2sharp', 'robidoux',
                'robidouxsharp', 'cosine', 'spline', 'sentinel')

#: (:class:`tuple`) The list of composition operators
#:
#: - ``'undefined'``
#: - ``'no'``
#: - ``'add'``
#: - ``'atop'``
#: - ``'blend'``
#: - ``'bumpmap'``
#: - ``'change_mask'``
#: - ``'clear'``
#: - ``'color_burn'``
#: - ``'color_dodge'``
#: - ``'colorize'``
#: - ``'copy_black'``
#: - ``'copy_blue'``
#: - ``'copy'``
#: - ``'copy_cyan'``
#: - ``'copy_green'``
#: - ``'copy_magenta'``
#: - ``'copy_opacity'``
#: - ``'copy_red'``
#: - ``'copy_yellow'``
#: - ``'darken'``
#: - ``'dst_atop'``
#: - ``'dst'``
#: - ``'dst_in'``
#: - ``'dst_out'``
#: - ``'dst_over'``
#: - ``'difference'``
#: - ``'displace'``
#: - ``'dissolve'``
#: - ``'exclusion'``
#: - ``'hard_light'``
#: - ``'hue'``
#: - ``'in'``
#: - ``'lighten'``
#: - ``'linear_light'``
#: - ``'luminize'``
#: - ``'minus'``
#: - ``'modulate'``
#: - ``'multiply'``
#: - ``'out'``
#: - ``'over'``
#: - ``'overlay'``
#: - ``'plus'``
#: - ``'replace'``
#: - ``'saturate'``
#: - ``'screen'``
#: - ``'soft_light'``
#: - ``'src_atop'``
#: - ``'src'``
#: - ``'src_in'``
#: - ``'src_out'``
#: - ``'src_over'``
#: - ``'subtract'``
#: - ``'threshold'``
#: - ``'xor'``
#: - ``'divide'``
#:
#: .. versionchanged:: 0.3.0
#:    Renamed from :const:`COMPOSITE_OPS` to :const:`COMPOSITE_OPERATORS`.
#:
#: .. seealso::
#:
#:    `Compositing Images`__ ImageMagick v6 Examples
#:       Image composition is the technique of combining images that have,
#:       or do not have, transparency or an alpha channel.
#:       This is usually performed using the IM :program:`composite` command.
#:       It may also be performed as either part of a larger sequence of
#:       operations or internally by other image operators.
#:
#:    `ImageMagick Composition Operators`__
#:       Demonstrates the results of applying the various composition
#:       composition operators.
#:
#:    __ http://www.imagemagick.org/Usage/compose/
#:    __ http://www.rubblewebs.co.uk/imagemagick/operators/compose.php
COMPOSITE_OPERATORS = (
    'undefined', 'no', 'add', 'atop', 'blend', 'bumpmap', 'change_mask',
    'clear', 'color_burn', 'color_dodge', 'colorize', 'copy_black',
    'copy_blue', 'copy', 'copy_cyan', 'copy_green', 'copy_magenta',
    'copy_opacity', 'copy_red', 'copy_yellow', 'darken', 'dst_atop', 'dst',
    'dst_in', 'dst_out', 'dst_over', 'difference', 'displace', 'dissolve',
    'exclusion', 'hard_light', 'hue', 'in', 'lighten', 'linear_light',
    'luminize', 'minus', 'modulate', 'multiply', 'out', 'over', 'overlay',
    'plus', 'replace', 'saturate', 'screen', 'soft_light', 'src_atop', 'src',
    'src_in', 'src_out', 'src_over', 'subtract', 'threshold', 'xor', 'divide'
)

#: (:class:`dict`) The dictionary of channel types.
#:
#: - ``'undefined'``
#: - ``'red'``
#: - ``'gray'``
#: - ``'cyan'``
#: - ``'green'``
#: - ``'magenta'``
#: - ``'blue'``
#: - ``'yellow'``
#: - ``'alpha'``
#: - ``'opacity'``
#: - ``'black'``
#: - ``'index'``
#: - ``'composite_channels'``
#: - ``'all_channels'``
#: - ``'true_alpha'``
#: - ``'rgb_channels'``
#: - ``'gray_channels'``
#: - ``'sync_channels'``
#: - ``'default_channels'``
#:
#: .. seealso::
#:
#:    `ImageMagick Color Channels`__
#:       Lists the various channel types with descriptions of each
#:
#:    __ http://www.imagemagick.org/Magick++/Enumerations.html#ChannelType
CHANNELS = dict(undefined=0, red=1, gray=1, cyan=1, green=2, magenta=2,
                blue=4, yellow=4, alpha=8, opacity=8, black=32, index=32,
                composite_channels=47, all_channels=134217727, true_alpha=64,
                rgb_channels=128, gray_channels=128, sync_channels=256,
                default_channels=134217719)

#: (:class:`tuple`) The list of evaluation operators
#:
#: - ``'undefined'``
#: - ``'add'``
#: - ``'and'``
#: - ``'divide'``
#: - ``'leftshift'``
#: - ``'max'``
#: - ``'min'``
#: - ``'multiply'``
#: - ``'or'``
#: - ``'rightshift'``
#: - ``'set'``
#: - ``'subtract'``
#: - ``'xor'``
#: - ``'pow'``
#: - ``'log'``
#: - ``'threshold'``
#: - ``'thresholdblack'``
#: - ``'thresholdwhite'``
#: - ``'gaussiannoise'``
#: - ``'impulsenoise'``
#: - ``'laplaciannoise'``
#: - ``'multiplicativenoise'``
#: - ``'poissonnoise'``
#: - ``'uniformnoise'``
#: - ``'cosine'``
#: - ``'sine'``
#: - ``'addmodulus'``
#: - ``'mean'``
#: - ``'abs'``
#: - ``'exponential'``
#: - ``'median'``
#: - ``'sum'``
#:
#: .. seealso::
#:
#:    `ImageMagick Image Evaluation Operators`__
#:       Describes the MagickEvaluateImageChannel method and lists the
#:       various evaluations operators
#:
#:    __ http://www.magickwand.org/MagickEvaluateImage.html
EVALUATE_OPS = ('undefined', 'add', 'and', 'divide', 'leftshift', 'max',
                'min', 'multiply', 'or', 'rightshift', 'set', 'subtract',
                'xor', 'pow', 'log', 'threshold', 'thresholdblack',
                'thresholdwhite', 'gaussiannoise', 'impulsenoise',
                'laplaciannoise', 'multiplicativenoise', 'poissonnoise',
                'uniformnoise', 'cosine', 'sine', 'addmodulus', 'mean',
                'abs', 'exponential', 'median', 'sum')

#: (:class:`tuple`) The list of colorspaces.
#:
#: - ``'undefined'``
#: - ``'rgb'``
#: - ``'gray'``
#: - ``'transparent'``
#: - ``'ohta'``
#: - ``'lab'``
#: - ``'xyz'``
#: - ``'ycbcr'``
#: - ``'ycc'``
#: - ``'yiq'``
#: - ``'ypbpr'``
#: - ``'yuv'``
#: - ``'cmyk'``
#: - ``'srgb'``
#: - ``'hsb'``
#: - ``'hsl'``
#: - ``'hwb'``
#: - ``'rec601luma'``
#: - ``'rec601ycbcr'``
#: - ``'rec709luma'``
#: - ``'rec709ycbcr'``
#: - ``'log'``
#: - ``'cmy'``
#: - ``'luv'``
#: - ``'hcl'``
#: - ``'lch'``
#: - ``'lms'``
#: - ``'lchab'``
#: - ``'lchuv'``
#: - ``'scrgb'``
#: - ``'hsi'``
#: - ``'hsv'``
#: - ``'hclp'``
#: - ``'ydbdr'``
#:
#: .. seealso::
#:
#:    `ImageMagick Color Management`__
#:       Describes the ImageMagick color management operations
#:
#:    __ http://www.imagemagick.org/script/color-management.php
#:
#: .. versionadded:: 0.3.4
COLORSPACE_TYPES = ('undefined', 'rgb', 'gray', 'transparent', 'ohta', 'lab',
                    'xyz', 'ycbcr', 'ycc', 'yiq', 'ypbpr', 'yuv', 'cmyk',
                    'srgb', 'hsb', 'hsl', 'hwb', 'rec601luma', 'rec601ycbcr',
                    'rec709luma', 'rec709ycbcr', 'log', 'cmy', 'luv', 'hcl',
                    'lch', 'lms', 'lchab', 'lchuv', 'scrgb', 'hsi', 'hsv',
                    'hclp', 'ydbdr')

#: (:class:`tuple`) The list of alpha channel types
#:
#: - ``'undefined'``
#: - ``'activate'``
#: - ``'background'``
#: - ``'copy'``
#: - ``'deactivate'``
#: - ``'extract'``
#: - ``'opaque'``
#: - ``'reset'``
#: - ``'set'``
#: - ``'shape'``
#: - ``'transparent'``
#: - ``'flatten'``
#: - ``'remove'``
#:
#: .. seealso::
#:    `ImageMagick Image Channel`__
#:       Describes the SetImageAlphaChannel method which can be used
#:       to modify alpha channel. Also describes AlphaChannelType
#:
#:    __ http://www.imagemagick.org/api/channel.php#SetImageAlphaChannel
ALPHA_CHANNEL_TYPES = ('undefined', 'activate', 'background', 'copy',
                       'deactivate', 'extract', 'opaque', 'reset', 'set',
                       'shape', 'transparent', 'flatten', 'remove')

#: (:class:`tuple`) The list of image types
#:
#: - ``'undefined'``
#: - ``'bilevel'``
#: - ``'grayscale'``
#: - ``'grayscalematte'``
#: - ``'palette'``
#: - ``'palettematte'``
#: - ``'truecolor'``
#: - ``'truecolormatte'``
#: - ``'colorseparation'``
#: - ``'colorseparationmatte'``
#: - ``'optimize'``
#: - ``'palettebilevelmatte'``
#:
#: .. seealso::
#:
#:    `ImageMagick Image Types`__
#:       Describes the MagickSetImageType method which can be used
#:       to set the type of an image
#:
#:    __ http://www.imagemagick.org/api/magick-image.php#MagickSetImageType
IMAGE_TYPES = ('undefined', 'bilevel', 'grayscale', 'grayscalematte',
               'palette', 'palettematte', 'truecolor', 'truecolormatte',
               'colorseparation', 'colorseparationmatte', 'optimize',
               'palettebilevelmatte')

#: (:class:`tuple`) The list of resolution unit types.
#:
#: - ``'undefined'``
#: - ``'pixelsperinch'``
#: - ``'pixelspercentimeter'``
#:
#: .. seealso::
#:
#:    `ImageMagick Image Units`__
#:       Describes the MagickSetImageUnits method which can be used
#:       to set image units of resolution
#:
#:    __ http://www.imagemagick.org/api/magick-image.php#MagickSetImageUnits
UNIT_TYPES = 'undefined', 'pixelsperinch', 'pixelspercentimeter'

#: (:class:`tuple`) The list of :attr:`~BaseImage.gravity` types.
#:
#: .. versionadded:: 0.3.0
GRAVITY_TYPES = ('forget', 'north_west', 'north', 'north_east', 'west',
                 'center', 'east', 'south_west', 'south', 'south_east',
                 'static')

#: (:class:`tuple`) The list of :attr:`~BaseImage.orientation` types.
#:
#: .. versionadded:: 0.3.0
ORIENTATION_TYPES = ('undefined', 'top_left', 'top_right', 'bottom_right',
                     'bottom_left', 'left_top', 'right_top', 'right_bottom',
                     'left_bottom')

#: (:class:`collections.Set`) The set of available :attr:`~BaseImage.options`.
#:
#: .. versionadded:: 0.3.0
#:
#: .. versionchanged:: 0.3.4
#:    Added ``'jpeg:sampling-factor'`` option.
OPTIONS = frozenset(['fill', 'jpeg:sampling-factor'])


def manipulative(function):
    """Mark the operation manipulating itself instead of returning new one."""
    @functools.wraps(function)
    def wrapped(self, *args, **kwargs):
        result = function(self, *args, **kwargs)
        self.dirty = True
        return result
    return wrapped


class BaseImage(Resource):
    """The abstract base of :class:`Image` (container) and
    :class:`~wand.sequence.SingleImage`.  That means the most of
    operations, defined in this abstract classs, are possible for
    both :class:`Image` and :class:`~wand.sequence.SingleImage`.

    .. versionadded:: 0.3.0

    """

    #: (:class:`OptionDict`) The mapping of internal option settings.
    #:
    #: .. versionadded:: 0.3.0
    #:
    #: .. versionchanged:: 0.3.4
    #:    Added ``'jpeg:sampling-factor'`` option.
    options = None

    #: (:class:`collections.Sequence`) The list of
    #: :class:`~wand.sequence.SingleImage`\ s that the image contains.
    #:
    #: .. versionadded:: 0.3.0
    sequence = None

    #: (:class:`bool`) Whether the image is changed or not.
    dirty = None

    c_is_resource = library.IsMagickWand
    c_destroy_resource = library.DestroyMagickWand
    c_get_exception = library.MagickGetException
    c_clear_exception = library.MagickClearException

    __slots__ = '_wand',

    def __init__(self, wand):
        self.wand = wand
        self.channel_images = ChannelImageDict(self)
        self.channel_depths = ChannelDepthDict(self)
        self.options = OptionDict(self)
        self.dirty = False

    @property
    def wand(self):
        """Internal pointer to the MagickWand instance. It may raise
        :exc:`ClosedImageError` when the instance has destroyed already.

        """
        try:
            return self.resource
        except DestroyedResourceError:
            raise ClosedImageError(repr(self) + ' is closed already')

    @wand.setter
    def wand(self, wand):
        try:
            self.resource = wand
        except TypeError:
            raise TypeError(repr(wand) + ' is not a MagickWand instance')

    @wand.deleter
    def wand(self):
        del self.resource

    def clone(self):
        """Clones the image. It is equivalent to call :class:`Image` with
        ``image`` parameter. ::

            with img.clone() as cloned:
                # manipulate the cloned image
                pass

        :returns: the cloned new image
        :rtype: :class:`Image`

        .. versionadded:: 0.1.1

        """
        return Image(image=self)

    def __len__(self):
        return self.height

    def __iter__(self):
        return Iterator(image=self)

    def __getitem__(self, idx):
        if (not isinstance(idx, string_type) and
            isinstance(idx, collections.Iterable)):
            idx = tuple(idx)
            d = len(idx)
            if not (1 <= d <= 2):
                raise ValueError('index cannot be {0}-dimensional'.format(d))
            elif d == 2:
                x, y = idx
                x_slice = isinstance(x, slice)
                y_slice = isinstance(y, slice)
                if x_slice and not y_slice:
                    y = slice(y, y + 1)
                elif not x_slice and y_slice:
                    x = slice(x, x + 1)
                elif not (x_slice or y_slice):
                    if not (isinstance(x, numbers.Integral) and
                            isinstance(y, numbers.Integral)):
                        raise TypeError('x and y must be integral, not ' +
                                        repr((x, y)))
                    if x < 0:
                        x += self.width
                    if y < 0:
                        y += self.height
                    if x >= self.width:
                        raise IndexError('x must be less than width')
                    elif y >= self.height:
                        raise IndexError('y must be less than height')
                    elif x < 0:
                        raise IndexError('x cannot be less than 0')
                    elif y < 0:
                        raise IndexError('y cannot be less than 0')
                    with iter(self) as iterator:
                        iterator.seek(y)
                        return iterator.next(x)
                if not (x.step is None and y.step is None):
                    raise ValueError('slicing with step is unsupported')
                elif (x.start is None and x.stop is None and
                      y.start is None and y.stop is None):
                    return self.clone()
                cloned = self.clone()
                try:
                    cloned.crop(x.start, y.start, x.stop, y.stop)
                except ValueError as e:
                    raise IndexError(str(e))
                return cloned
            else:
                return self[idx[0]]
        elif isinstance(idx, numbers.Integral):
            if idx < 0:
                idx += self.height
            elif idx >= self.height:
                raise IndexError('index must be less than height, but got ' +
                                 repr(idx))
            elif idx < 0:
                raise IndexError('index cannot be less than zero, but got ' +
                                 repr(idx))
            with iter(self) as iterator:
                iterator.seek(idx)
                return iterator.next()
        elif isinstance(idx, slice):
            return self[:, idx]
        raise TypeError('unsupported index type: ' + repr(idx))

    def __eq__(self, other):
        if isinstance(other, type(self)):
            return self.signature == other.signature
        return False

    def __ne__(self, other):
        return not (self == other)

    def __hash__(self):
        return hash(self.signature)

    @property
    def animation(self):
        """(:class:`bool`) Whether the image is animation or not.
        It doesn't only mean that the image has two or more images (frames),
        but all frames are even the same size.  It's about image format,
        not content.  It's :const:`False` even if :mimetype:`image/ico`
        consits of two or more images of the same size.

        For example, it's :const:`False` for :mimetype:`image/jpeg`,
        :mimetype:`image/gif`, :mimetype:`image/ico`.

        If :mimetype:`image/gif` has two or more frames, it's :const:`True`.
        If :mimetype:`image/gif` has only one frame, it's :const:`False`.

        .. versionadded:: 0.3.0

        """
        return False

    @property
    def gravity(self):
        """(:class:`basestring`) The text placement gravity used when
        annotating with text.  It's a string from :const:`GRAVITY_TYPES`
        list.  It also can be set.

        """
        gravity_index = library.MagickGetGravity(self.wand)
        if not gravity_index:
            self.raise_exception()
        return GRAVITY_TYPES[gravity_index]

    @gravity.setter
    @manipulative
    def gravity(self, value):
        if not isinstance(value, string_type):
            raise TypeError('expected a string, not ' + repr(value))
        if value not in GRAVITY_TYPES:
            raise ValueError('expected a string from GRAVITY_TYPES, not '
                             + repr(value))
        library.MagickSetGravity(self.wand, GRAVITY_TYPES.index(value))

    @property
    def font_path(self):
        """(:class:`basestring`) The path of the current font.
        It also can be set.

        """
        return text(library.MagickGetFont(self.wand))

    @font_path.setter
    @manipulative
    def font_path(self, font):
        font = binary(font)
        if library.MagickSetFont(self.wand, font) == False:
            raise ValueError('font is invalid')

    @property
    def font_size(self):
        """(:class:`numbers.Real`) The font size.  It also can be set."""
        return library.MagickGetPointsize(self.wand)

    @font_size.setter
    @manipulative
    def font_size(self, size):
        if not isinstance(size, numbers.Real):
            raise TypeError('expected a numbers.Real, but got ' + repr(size))
        elif size < 0.0:
            raise ValueError('cannot be less then 0.0, but got ' + repr(size))
        elif library.MagickSetPointsize(self.wand, size) == False:
            raise ValueError('unexpected error is occur')

    @property
    def font_antialias(self):
        return bool(library.MagickGetAntialias(self.wand))

    @font_antialias.setter
    @manipulative
    def font_antialias(self, antialias):
        if not isinstance(antialias, bool):
            raise TypeError('font_antialias must be a bool, not ' +
                            repr(antialias))
        library.MagickSetAntialias(self.wand, antialias)

    @property
    def font(self):
        """(:class:`wand.font.Font`) The current font options."""
        return Font(
            path=text(self.font_path),
            size=self.font_size,
            color=self.font_color,
            antialias=self.font_antialias
        )

    @font.setter
    @manipulative
    def font(self, font):
        if not isinstance(font, Font):
            raise TypeError('font must be a wand.font.Font, not ' + repr(font))
        self.font_path = font.path
        self.font_size = font.size
        self.font_color = font.color
        self.font_antialias = font.antialias

    @property
    def width(self):
        """(:class:`numbers.Integral`) The width of this image."""
        return library.MagickGetImageWidth(self.wand)

    @width.setter
    @manipulative
    def width(self, width):
        if width is not None and not isinstance(width, numbers.Integral):
            raise TypeError('width must be a integral, not ' + repr(width))
        library.MagickSetSize(self.wand, width, self.height)

    @property
    def height(self):
        """(:class:`numbers.Integral`) The height of this image."""
        return library.MagickGetImageHeight(self.wand)

    @height.setter
    @manipulative
    def height(self, height):
        if height is not None and not isinstance(height, numbers.Integral):
            raise TypeError('height must be a integral, not ' + repr(height))
        library.MagickSetSize(self.wand, self.width, height)

    @property
    def orientation(self):
        """(:class:`basestring`) The image orientation.  It's a string from
        :const:`ORIENTATION_TYPES` list.  It also can be set.

        .. versionadded:: 0.3.0
        
        """
        orientation_index = library.MagickGetImageOrientation(self.wand)
        return ORIENTATION_TYPES[text(orientation_index)]

    @orientation.setter
    @manipulative
    def orientation(self, value):
        if not isinstance(value, string_type):
            raise TypeError('expected a string, not ' + repr(value))
        if value not in ORIENTATION_TYPES:
            raise ValueError('expected a string from ORIENTATION_TYPES, not '
                             + repr(value))
        index = ORIENTATION_TYPES.index(value)
        library.MagickSetImageOrientation(self.wand, index)

    @property
    def font_color(self):
        return Color(self.options['fill'])

    @font_color.setter
    @manipulative
    def font_color(self, color):
        if not isinstance(color, Color):
            raise TypeError('font_color must be a wand.color.Color, not ' +
                            repr(color))
        self.options['fill'] = color.string

    @manipulative
    def caption(self, text, left=0, top=0, width=None, height=None, font=None,
                gravity=None):
        """Writes a caption ``text`` into the position.

        :param text: text to write
        :type text: :class:`basestring`
        :param left: x offset in pixels
        :type left: :class:`numbers.Integral`
        :param right: y offset in pixels
        :type right: :class:`numbers.Integral`
        :param width: width of caption in pixels.
                      default is :attr:`width` of the image
        :type width: :class:`numbers.Integral`
        :param height: height of caption in pixels.
                       default is :attr:`height` of the image
        :type height: :class:`numbers.Integral`
        :param font: font to use.  default is :attr:`font` of the image
        :type font: :class:`wand.font.Font`
        :param gravity: text placement gravity.
                        uses the current :attr:`gravity` setting of the image
                        by default
        :type gravity: :class:`basestring`

        .. versionadded:: 0.3.0

        """
        if not isinstance(left, numbers.Integral):
            raise TypeError('left must be an integer, not ' + repr(left))
        elif not isinstance(top, numbers.Integral):
            raise TypeError('top must be an integer, not ' + repr(top))
        elif width is not None and not isinstance(width, numbers.Integral):
            raise TypeError('width must be an integer, not ' + repr(width))
        elif height is not None and not isinstance(height, numbers.Integral):
            raise TypeError('height must be an integer, not ' + repr(height))
        elif font is not None and not isinstance(font, Font):
            raise TypeError('font must be a wand.font.Font, not ' + repr(font))
        elif gravity is not None and compat.text(gravity) not in GRAVITY_TYPES:
            raise ValueError('invalid gravity value')
        if width is None:
            width = self.width - left
        if height is None:
            height = self.height - top
        with Image() as textboard:
            library.MagickSetSize(textboard.wand, width, height)
            textboard.font = font or self.font
            textboard.gravity = gravity or self.gravity
            with Color('transparent') as background_color:
                library.MagickSetBackgroundColor(textboard.wand,
                                                 background_color.resource)
            textboard.read(filename=b'caption:' + text.encode('utf-8'))
            self.composite(textboard, left, top)


    @property
    def resolution(self):
        """(:class:`tuple`) Resolution of this image.

        .. versionadded:: 0.3.0

        """
        x = ctypes.c_double()
        y = ctypes.c_double()
        r = library.MagickGetImageResolution(self.wand, x, y)
        if not r:
            self.raise_exception()
        return int(x.value), int(y.value)

    @resolution.setter
    @manipulative
    def resolution(self, geometry):
        if isinstance(geometry, collections.Sequence):
            x, y = geometry
        elif isinstance(geometry, numbers.Integral):
            x, y = geometry, geometry
        else:
            raise TypeError('resolution must be a (x, y) pair or an integer '
                            'of the same x/y')
        if self.size == (0, 0):
            r = library.MagickSetResolution(self.wand, x, y)
        else:
            r = library.MagickSetImageResolution(self.wand, x, y)
        if not r:
            self.raise_exception()

    @property
    def size(self):
        """(:class:`tuple`) The pair of (:attr:`width`, :attr:`height`)."""
        return self.width, self.height

    @property
    def units(self):
        """(:class:`basestring`) The resolution units of this image."""
        r = library.MagickGetImageUnits(self.wand)
        return UNIT_TYPES[text(r)]

    @units.setter
    @manipulative
    def units(self, units):
        if not isinstance(units, string_type) or units not in UNIT_TYPES:
            raise TypeError('Unit value must be a string from wand.images.'
                            'UNIT_TYPES, not ' + repr(units))
        r = library.MagickSetImageUnits(self.wand, UNIT_TYPES.index(units))
        if not r:
            self.raise_exception()

    @property
    def colorspace(self):
        """(:class:`basestring`) The image colorspace.

        Defines image colorspace as in :const:`COLORSPACE_TYPES` enumeration.

        It may raise :exc:`ValueError` when the colorspace is unknown.

        .. versionadded:: 0.3.4

        """
        colorspace_type_index = library.MagickGetImageColorspace(self.wand)
        if not colorspace_type_index:
            self.raise_exception()
        return COLORSPACE_TYPES[text(colorspace_type_index)]

    @colorspace.setter
    @manipulative
    def colorspace(self, colorspace_type):
        if not isinstance(colorspace_type, string_type) \
            or colorspace_type not in COLORSPACE_TYPES:
            raise TypeError('Colorspace value must be a string from '
                            'COLORSPACE_TYPES, not ' + repr(colorspace_type))
        r = library.MagickSetImageColorspace(self.wand,
                                    COLORSPACE_TYPES.index(colorspace_type))
        if not r:
            self.raise_exception()

    @property
    def depth(self):
        """(:class:`numbers.Integral`) The depth of this image.

        .. versionadded:: 0.2.1

        """
        return library.MagickGetImageDepth(self.wand)

    @depth.setter
    @manipulative
    def depth(self, depth):
        r = library.MagickSetImageDepth(self.wand, depth)
        if not r:
            raise self.raise_exception()

    @property
    def type(self):
        """(:class:`basestring`) The image type.

        Defines image type as in :const:`IMAGE_TYPES` enumeration.

        It may raise :exc:`ValueError` when the type is unknown.

        .. versionadded:: 0.2.2

        """
        image_type_index = library.MagickGetImageType(self.wand)
        if not image_type_index:
            self.raise_exception()
        return IMAGE_TYPES[text(image_type_index)]

    @type.setter
    @manipulative
    def type(self, image_type):
        if not isinstance(image_type, string_type) \
            or image_type not in IMAGE_TYPES:
            raise TypeError('Type value must be a string from IMAGE_TYPES'
                            ', not ' + repr(image_type))
        r = library.MagickSetImageType(self.wand,
                                       IMAGE_TYPES.index(image_type))
        if not r:
            self.raise_exception()

    @property
    def compression_quality(self):
        """(:class:`numbers.Integral`) Compression quality of this image.

        .. versionadded:: 0.2.0

        """
        return library.MagickGetImageCompressionQuality(self.wand)

    @compression_quality.setter
    @manipulative
    def compression_quality(self, quality):
        """Set compression quality for the image.

        :param quality: new compression quality setting
        :type quality: :class:`numbers.Integral`

        """
        if not isinstance(quality, numbers.Integral):
            raise TypeError('compression quality must be a natural '
                            'number, not ' + repr(quality))
        r = library.MagickSetImageCompressionQuality(self.wand, quality)
        if not r:
            raise ValueError('Unable to set compression quality to ' +
                             repr(quality))

    @property
    def signature(self):
        """(:class:`str`) The SHA-256 message digest for the image pixel
        stream.

        .. versionadded:: 0.1.9

        """
        signature = library.MagickGetImageSignature(self.wand)
        return text(signature.value)

    @property
    def alpha_channel(self):
        """(:class:`bool`) Get state of image alpha channel.
        It can also be used to enable/disable alpha channel.

        .. versionadded:: 0.2.1

        .. todo::

           Support other states than ``''activatealphachannel'``
           or ``'deactivatealphachannel'``.

        """
        return bool(library.MagickGetImageAlphaChannel(self.wand))

    @alpha_channel.setter
    @manipulative
    def alpha_channel(self, alpha):
        if alpha == True:
            act = ALPHA_CHANNEL_TYPES.index('activate')
        elif alpha == False:
            act = ALPHA_CHANNEL_TYPES.index('deactivate')
        else:
            raise TypeError('alpha_channel must be bool, not ' +
                            repr(alpha))
        r = library.MagickSetImageAlphaChannel(self.wand, act)
        if r:
            return r
        self.raise_exception()

    @property
    def background_color(self):
        """(:class:`wand.color.Color`) The image background color.
        It can also be set to change the background color.

        .. versionadded:: 0.1.9

        """
        pixel = library.NewPixelWand()
        result = library.MagickGetImageBackgroundColor(self.wand, pixel)
        if result:
            size = ctypes.sizeof(MagickPixelPacket)
            buffer = ctypes.create_string_buffer(size)
            library.PixelGetMagickColor(pixel, buffer)
            return Color(raw=buffer)
        self.raise_exception()

    @background_color.setter
    @manipulative
    def background_color(self, color):
        if not isinstance(color, Color):
            raise TypeError('color must be a wand.color.Color object, not ' +
                            repr(color))
        with color:
            result = library.MagickSetImageBackgroundColor(self.wand,
                                                           color.resource)
            if not result:
                self.raise_exception()

    @property
    def quantum_range(self):
        """(:class:`int`) The maxumim value of a color channel that is
        supported by the imagemgick library.

        .. versionadded:: 0.2.0

        """
        result = ctypes.c_size_t()
        library.MagickGetQuantumRange(ctypes.byref(result))
        return result.value

    @property
    def histogram(self):
        """(:class:`HistogramDict`) The mapping that represents the histogram.
        Keys are :class:`~wand.color.Color` objects, and values are
        the number of pixels.

        .. versionadded:: 0.3.0

        """
        return HistogramDict(self)

    @manipulative
    def crop(self, left=0, top=0, right=None, bottom=None,
             width=None, height=None, reset_coords=True):
        """Crops the image in-place.

        .. sourcecode:: text

           +--------------------------------------------------+
           |              ^                         ^         |
           |              |                         |         |
           |             top                        |         |
           |              |                         |         |
           |              v                         |         |
           | <-- left --> +-------------------+  bottom       |
           |              |             ^     |     |         |
           |              | <-- width --|---> |     |         |
           |              |           height  |     |         |
           |              |             |     |     |         |
           |              |             v     |     |         |
           |              +-------------------+     v         |
           | <--------------- right ---------->               |
           +--------------------------------------------------+

        :param left: x-offset of the cropped image. default is 0
        :type left: :class:`numbers.Integral`
        :param top: y-offset of the cropped image. default is 0
        :type top: :class:`numbers.Integral`
        :param right: second x-offset of the cropped image.
                      default is the :attr:`width` of the image.
                      this parameter and ``width`` parameter are exclusive
                      each other
        :type right: :class:`numbers.Integral`
        :param bottom: second y-offset of the cropped image.
                       default is the :attr:`height` of the image.
                       this parameter and ``height`` parameter are exclusive
                       each other
        :type bottom: :class:`numbers.Integral`
        :param width: the :attr:`width` of the cropped image.
                      default is the :attr:`width` of the image.
                      this parameter and ``right`` parameter are exclusive
                      each other
        :type width: :class:`numbers.Integral`
        :param height: the :attr:`height` of the cropped image.
                       default is the :attr:`height` of the image.
                       this parameter and ``bottom`` parameter are exclusive
                       each other
        :type height: :class:`numbers.Integral`
        :param reset_coords:
           optional flag. If set, after the rotation, the coordinate frame
           will be relocated to the upper-left corner of the new image.
           By default is `True`.
        :type reset_coords: :class:`bool`
        :raises exceptions.ValueError:
           when one or more arguments are invalid

        .. note::

           If you want to crop the image but not in-place, use slicing
           operator.

        .. versionchanged:: 0.1.8
           Made to raise :exc:`~exceptions.ValueError` instead of
           :exc:`~exceptions.IndexError` for invalid ``width``/``height``
           arguments.

        .. versionadded:: 0.1.7

        """
        if not (right is None or width is None):
            raise TypeError('parameters right and width are exclusive each '
                            'other; use one at a time')
        elif not (bottom is None or height is None):
            raise TypeError('parameters bottom and height are exclusive each '
                            'other; use one at a time')
        def abs_(n, m, null=None):
            if n is None:
                return m if null is None else null
            elif not isinstance(n, numbers.Integral):
                raise TypeError('expected integer, not ' + repr(n))
            elif n > m:
                raise ValueError(repr(n) + ' > ' + repr(m))
            return m + n if n < 0 else n
        left = abs_(left, self.width, 0)
        top = abs_(top, self.height, 0)
        if width is None:
            right = abs_(right, self.width)
            width = right - left
        if height is None:
            bottom = abs_(bottom, self.height)
            height = bottom - top
        if width < 1:
            raise ValueError('image width cannot be zero')
        elif height < 1:
            raise ValueError('image width cannot be zero')
        elif left == top == 0 and width == self.width and height == self.height:
            return
        if self.animation:
            self.wand = library.MagickCoalesceImages(self.wand)
            library.MagickSetLastIterator(self.wand)
            n = library.MagickGetIteratorIndex(self.wand)
            library.MagickResetIterator(self.wand)
            for i in xrange(0, n + 1):
                library.MagickSetIteratorIndex(self.wand, i)
                library.MagickCropImage(self.wand, width, height, left, top)
                if reset_coords:
                    library.MagickResetImagePage(self.wand, None)
        else:
            library.MagickCropImage(self.wand, width, height, left, top)
            self.raise_exception()
            if reset_coords:
                self.reset_coords()

    def reset_coords(self):
        """Reset the coordinate frame of the image so to the upper-left corner
        is (0, 0) again (crop and rotate operations change it).

        .. versionadded:: 0.2.0

        """
        library.MagickResetImagePage(self.wand, None)

    @manipulative
    def resize(self, width=None, height=None, filter='undefined', blur=1):
        """Resizes the image.

        :param width: the width in the scaled image. default is the original
                      width
        :type width: :class:`numbers.Integral`
        :param height: the height in the scaled image. default is the original
                       height
        :type height: :class:`numbers.Integral`
        :param filter: a filter type to use for resizing. choose one in
                       :const:`FILTER_TYPES`. default is ``'undefined'``
                       which means IM will try to guess best one to use
        :type filter: :class:`basestring`, :class:`numbers.Integral`
        :param blur: the blur factor where > 1 is blurry, < 1 is sharp.
                     default is 1
        :type blur: :class:`numbers.Real`

        .. versionchanged:: 0.2.1
           The default value of ``filter`` has changed from ``'triangle'``
           to ``'undefined'`` instead.

        .. versionchanged:: 0.1.8
           The ``blur`` parameter changed to take :class:`numbers.Real`
           instead of :class:`numbers.Rational`.

        .. versionadded:: 0.1.1

        """
        if width is None:
            width = self.width
        if height is None:
            height = self.height
        if not isinstance(width, numbers.Integral):
            raise TypeError('width must be a natural number, not ' +
                            repr(width))
        elif not isinstance(height, numbers.Integral):
            raise TypeError('height must be a natural number, not ' +
                            repr(height))
        elif width < 1:
            raise ValueError('width must be a natural number, not ' +
                             repr(width))
        elif height < 1:
            raise ValueError('height must be a natural number, not ' +
                             repr(height))
        elif not isinstance(blur, numbers.Real):
            raise TypeError('blur must be numbers.Real , not ' + repr(blur))
        elif not isinstance(filter, (string_type, numbers.Integral)):
            raise TypeError('filter must be one string defined in wand.image.'
                            'FILTER_TYPES or an integer, not ' + repr(filter))
        if isinstance(filter, string_type):
            try:
                filter = FILTER_TYPES.index(filter)
            except IndexError:
                raise ValueError(repr(filter) + ' is an invalid filter type; '
                                 'choose on in ' + repr(FILTER_TYPES))
        elif (isinstance(filter, numbers.Integral) and
              not (0 <= filter < len(FILTER_TYPES))):
            raise ValueError(repr(filter) + ' is an invalid filter type')
        blur = ctypes.c_double(float(blur))
        if self.animation:
            self.wand = library.MagickCoalesceImages(self.wand)
            library.MagickSetLastIterator(self.wand)
            n = library.MagickGetIteratorIndex(self.wand)
            library.MagickResetIterator(self.wand)
            for i in xrange(n + 1):
                library.MagickSetIteratorIndex(self.wand, i)
                library.MagickResizeImage(self.wand, width, height,
                                          filter, blur)
            library.MagickSetSize(self.wand, width, height)
        else:
            r = library.MagickResizeImage(self.wand, width, height,
                                          filter, blur)
            library.MagickSetSize(self.wand, width, height)
            if not r:
                self.raise_exception()
                
    @manipulative
    def sample(self, width=None, height=None):
        """Resizes the image by sampling the pixels.  It's basically quicker
        than :meth:`resize()` except less quality as a tradeoff.

        :param width: the width in the scaled image. default is the original
                      width
        :type width: :class:`numbers.Integral`
        :param height: the height in the scaled image. default is the original
                       height
        :type height: :class:`numbers.Integral`

        .. versionadded:: 0.3.4

        """
        if width is None:
            width = self.width
        if height is None:
            height = self.height
        if not isinstance(width, numbers.Integral):
            raise TypeError('width must be a natural number, not ' +
                            repr(width))
        elif not isinstance(height, numbers.Integral):
            raise TypeError('height must be a natural number, not ' +
                            repr(height))
        elif width < 1:
            raise ValueError('width must be a natural number, not ' +
                             repr(width))
        elif height < 1:
            raise ValueError('height must be a natural number, not ' +
                             repr(height))
        if self.animation:
            self.wand = library.MagickCoalesceImages(self.wand)
            library.MagickSetLastIterator(self.wand)
            n = library.MagickGetIteratorIndex(self.wand)
            library.MagickResetIterator(self.wand)
            for i in xrange(n + 1):
                library.MagickSetIteratorIndex(self.wand, i)
                library.MagickSampleImage(self.wand, width, height)
            library.MagickSetSize(self.wand, width, height)
        else:
            r = library.MagickSampleImage(self.wand, width, height)
            library.MagickSetSize(self.wand, width, height)
            if not r:
                self.raise_exception()

    @manipulative
    def transform(self, crop='', resize=''):
        """Transforms the image using :c:func:`MagickTransformImage`,
        which is a convenience function accepting geometry strings to
        perform cropping and resizing.  Cropping is performed first,
        followed by resizing.  Either or both arguments may be omitted
        or given an empty string, in which case the corresponding action
        will not be performed. Geometry specification strings are
        defined as follows:

        A geometry string consists of a size followed by an optional offset.
        The size is specified by one of the options below,
        where **bold** terms are replaced with appropriate integer values:

        **scale**\ ``%``
          Height and width both scaled by specified percentage

        **scale-x**\ ``%x``\ \ **scale-y**\ ``%``
          Height and width individually scaled by specified percentages.
          Only one % symbol is needed.

        **width**
          Width given, height automagically selected to preserve aspect ratio.

        ``x``\ \ **height**
          Height given, width automagically selected to preserve aspect ratio.

        **width**\ ``x``\ **height**
          Maximum values of width and height given; aspect ratio preserved.

        **width**\ ``x``\ **height**\ ``!``
          Width and height emphatically given; original aspect ratio ignored.

        **width**\ ``x``\ **height**\ ``>``
          Shrinks images with dimension(s) larger than the corresponding
          width and/or height dimension(s).

        **width**\ ``x``\ **height**\ ``<``
          Enlarges images with dimensions smaller than the corresponding
          width and/or height dimension(s).

        **area**\ ``@``
          Resize image to have the specified area in pixels.
          Aspect ratio is preserved.

        The offset, which only applies to the cropping geometry string,
        is given by ``{+-}``\ **x**\ ``{+-}``\ **y**\ , that is,
        one plus or minus sign followed by an **x** offset,
        followed by another plus or minus sign, followed by a **y** offset.
        Offsets are in pixels from the upper left corner of the image.
        Negative offsets will cause the corresponding number of pixels to
        be removed from the right or bottom edge of the image, meaning the
        cropped size will be the computed size minus the absolute value
        of the offset.

        For example, if you want to crop your image to 300x300 pixels
        and then scale it by 2x for a final size of 600x600 pixels,
        you can call::

            image.transform('300x300', '200%')

        This method is a fairly thing wrapper for the C API, and does not
        perform any additional checking of the parameters except insofar as
        verifying that they are of the correct type.  Thus, like the C
        API function, the method is very permissive in terms of what
        it accepts for geometry strings; unrecognized strings and
        trailing characters will be ignored rather than raising an error.

        :param crop: A geometry string defining a subregion of the image
                     to crop to
        :type crop: :class:`basestring`
        :param resize: A geometry string defining the final size of the image
        :type resize: :class:`basestring`

        .. seealso::

           `ImageMagick Geometry Specifications`__
              Cropping and resizing geometry for the ``transform`` method are
              specified according to ImageMagick's geometry string format.
              The ImageMagick documentation provides more information about
              geometry strings.

           __ http://www.imagemagick.org/script/command-line-processing.php#geometry

        .. versionadded:: 0.2.2

        """
        # Check that the values given are the correct types.  ctypes will do
        # this automatically, but we can make the error message more friendly
        # here.
        if not isinstance(crop, string_type):
            raise TypeError("crop must be a string, not " + repr(crop))
        if not isinstance(resize, string_type):
            raise TypeError("resize must be a string, not " + repr(resize))
        # Also verify that only ASCII characters are included
        try:
            crop = crop.encode('ascii')
        except UnicodeEncodeError:
            raise ValueError('crop must only contain ascii-encodable ' +
                             'characters.')
        try:
            resize = resize.encode('ascii')
        except UnicodeEncodeError:
            raise ValueError('resize must only contain ascii-encodable ' +
                             'characters.')
        if self.animation:
            new_wand = library.MagickCoalesceImages(self.wand)
            length = len(self.sequence)
            for i in xrange(length):
                library.MagickSetIteratorIndex(new_wand, i)
                if i:
                    library.MagickAddImage(
                        new_wand,
                        library.MagickTransformImage(new_wand, crop, resize)
                    )
                else:
                    new_wand = library.MagickTransformImage(new_wand,
                                                            crop,
                                                            resize)
            self.sequence.instances = []
        else:
            new_wand = library.MagickTransformImage(self.wand, crop, resize)
        if not new_wand:
            self.raise_exception()
        self.wand = new_wand

    @manipulative
    def liquid_rescale(self, width, height, delta_x=0, rigidity=0):
        """Rescales the image with `seam carving`_, also known as
        image retargeting, content-aware resizing, or liquid rescaling.

        :param width: the width in the scaled image
        :type width: :class:`numbers.Integral`
        :param height: the height in the scaled image
        :type height: :class:`numbers.Integral`
        :param delta_x: maximum seam transversal step.
                        0 means straight seams.  default is 0
        :type delta_x: :class:`numbers.Real`
        :param rigidity: introduce a bias for non-straight seams.
                         default is 0
        :type rigidity: :class:`numbers.Real`
        :raises wand.exceptions.MissingDelegateError:
           when ImageMagick isn't configured ``--with-lqr`` option.

        .. note::

           This feature requires ImageMagick to be configured
           ``--with-lqr`` option.  Or it will raise
           :exc:`~wand.exceptions.MissingDelegateError`:

        .. seealso::

           `Seam carving`_ --- Wikipedia
              The article which explains what seam carving is
              on Wikipedia.

        .. _Seam carving: http://en.wikipedia.org/wiki/Seam_carving

        """
        if not isinstance(width, numbers.Integral):
            raise TypeError('width must be an integer, not ' + repr(width))
        elif not isinstance(height, numbers.Integral):
            raise TypeError('height must be an integer, not ' + repr(height))
        elif not isinstance(delta_x, numbers.Real):
            raise TypeError('delta_x must be a float, not ' + repr(delta_x))
        elif not isinstance(rigidity, numbers.Real):
            raise TypeError('rigidity must be a float, not ' + repr(rigidity))
        library.MagickLiquidRescaleImage(self.wand, int(width), int(height),
                                         float(delta_x), float(rigidity))
        self.raise_exception()

    @manipulative
    def rotate(self, degree, background=None, reset_coords=True):
        """Rotates the image right.  It takes a ``background`` color
        for ``degree`` that isn't a multiple of 90.

        :param degree: a degree to rotate. multiples of 360 affect nothing
        :type degree: :class:`numbers.Real`
        :param background: an optional background color.
                           default is transparent
        :type background: :class:`wand.color.Color`
        :param reset_coords: optional flag. If set, after the rotation, the
            coordinate frame will be relocated to the upper-left corner of
            the new image. By default is `True`.
        :type reset_coords: :class:`bool`

        .. versionadded:: 0.2.0
           The ``reset_coords`` parameter.

        .. versionadded:: 0.1.8

        """
        if background is None:
            background = Color('transparent')
        elif not isinstance(background, Color):
            raise TypeError('background must be a wand.color.Color instance, '
                            'not ' + repr(background))
        if not isinstance(degree, numbers.Real):
            raise TypeError('degree must be a numbers.Real value, not ' +
                            repr(degree))
        with background:
            if self.animation:
                self.wand = library.MagickCoalesceImages(self.wand)
                library.MagickSetLastIterator(self.wand)
                n = library.MagickGetIteratorIndex(self.wand)
                library.MagickResetIterator(self.wand)
                for i in range(0, n + 1):
                    library.MagickSetIteratorIndex(self.wand, i)
                    library.MagickRotateImage(self.wand,
                                              background.resource,
                                              degree)
                    if reset_coords:
                        library.MagickResetImagePage(self.wand, None)
            else:
                result = library.MagickRotateImage(self.wand,
                                                   background.resource,
                                                   degree)
                if not result:
                    self.raise_exception()
                if reset_coords:
                    self.reset_coords()

    @manipulative
    def flip(self):
        """Creates a vertical mirror image by reflecting the pixels around
        the central x-axis.  It manipulates the image in place.

        .. versionadded:: 0.3.0

        """
        result = library.MagickFlipImage(self.wand)
        if not result:
            self.raise_exception()

    @manipulative
    def flop(self):
        """Creates a horizontal mirror image by reflecting the pixels around
        the central y-axis.  It manipulates the image in place.

        .. versionadded:: 0.3.0

        """
        result = library.MagickFlopImage(self.wand)
        if not result:
            self.raise_exception()

    @manipulative
    def transparentize(self, transparency):
        """Makes the image transparent by subtracting some percentage of
        the black color channel.  The ``transparency`` parameter specifies the
        percentage.

        :param transparency: the percentage fade that should be performed on the
                             image, from 0.0 to 1.0
        :type transparency: :class:`numbers.Real`

        .. versionadded:: 0.2.0

        """
        if transparency:
            t = ctypes.c_double(float(self.quantum_range * float(transparency)))
            if t.value > self.quantum_range or t.value < 0:
                raise ValueError('transparency must be a numbers.Real value ' +
                                 'between 0.0 and 1.0')
            # Set the wand to image zero, in case there are multiple images
            # in it
            library.MagickSetIteratorIndex(self.wand, 0)
            # Change the pixel representation of the image
            # to RGB with an alpha channel
            library.MagickSetImageType(self.wand,
                                       IMAGE_TYPES.index('truecolormatte'))
            # Perform the black channel subtraction
            library.MagickEvaluateImageChannel(self.wand,
                                               CHANNELS['opacity'],
                                               EVALUATE_OPS.index('subtract'),
                                               t)
            self.raise_exception()

    @manipulative
    def transparent_color(self, color, alpha, fuzz=0, invert=False):
        """Makes the color ``color`` a transparent color with a tolerance of
        fuzz. The ``alpha`` parameter specify the transparency level and the
        parameter ``fuzz`` specify the tolerance.

        :param color: The color that should be made transparent on the image,
                      color object
        :type color: :class:`wand.color.Color`
        :param alpha: the level of transparency: 1.0 is fully opaque
                      and 0.0 is fully transparent.
        :type alpha: :class:`numbers.Real`
        :param fuzz: By default target must match a particular pixel color
                     exactly. However, in many cases two colors may differ
                     by a small amount. The fuzz member of image defines how
                     much tolerance is acceptable to consider two colors as the
                     same. For example, set fuzz to 10 and the color red at
                     intensities of 100 and 102 respectively are now interpreted
                     as the same color for the color.
        :type fuzz: :class:`numbers.Integral`
        :param invert: Boolean to tell to paint the inverse selection.
        :type invert: :class:`bool`

        .. versionadded:: 0.3.0

        """
        if not isinstance(alpha, numbers.Real):
            raise TypeError('alpha must be an float, not ' + repr(alpha))
        elif not isinstance(fuzz, numbers.Integral):
            raise TypeError('fuzz must be an integer, not ' + repr(fuzz))
        elif not isinstance(color, Color):
            raise TypeError('color must be a wand.color.Color object, not ' +
                            repr(color))
        library.MagickTransparentPaintImage(self.wand, color.resource,
                                            alpha, fuzz, invert)
        self.raise_exception()

    @manipulative
    def composite(self, image, left, top):
        """Places the supplied ``image`` over the current image, with the top
        left corner of ``image`` at coordinates ``left``, ``top`` of the
        current image.  The dimensions of the current image are not changed.

        :param image: the image placed over the current image
        :type image: :class:`wand.image.Image`
        :param left: the x-coordinate where `image` will be placed
        :type left: :class:`numbers.Integral`
        :param top: the y-coordinate where `image` will be placed
        :type top: :class:`numbers.Integral`

        .. versionadded:: 0.2.0

        """
        if not isinstance(left, numbers.Integral):
            raise TypeError('left must be an integer, not ' + repr(left))
        elif not isinstance(top, numbers.Integral):
            raise TypeError('top must be an integer, not ' + repr(left))
        op = COMPOSITE_OPERATORS.index('over')
        library.MagickCompositeImage(self.wand, image.wand, op,
                                     int(left), int(top))
        self.raise_exception()

    @manipulative
    def composite_channel(self, channel, image, operator, left=0, top=0):
        """Composite two images using the particular ``channel``.

        :param channel: the channel type.  available values can be found
                        in the :const:`CHANNELS` mapping
        :param image: the composited source image.
                      (the receiver image becomes the destination)
        :type image: :class:`Image`
        :param operator: the operator that affects how the composite
                         is applied to the image.  available values
                         can be found in the :const:`COMPOSITE_OPERATORS`
                         list
        :param left: the column offset of the composited source image
        :type left: :class:`numbers.Integral`
        :param top: the row offset of the composited source image
        :type top: :class:`numbers.Integral`
        :raises exceptions.ValueError: when the given ``channel`` or
                                       ``operator`` is invalid

        .. versionadded:: 0.3.0

        """
        if not isinstance(channel, string_type):
            raise TypeError('channel must be a string, not ' +
                            repr(channel))
        elif not isinstance(operator, string_type):
            raise TypeError('operator must be a string, not ' +
                            repr(operator))
        elif not isinstance(left, numbers.Integral):
            raise TypeError('left must be an integer, not ' + repr(left))
        elif not isinstance(top, numbers.Integral):
            raise TypeError('top must be an integer, not ' + repr(left))
        try:
            ch_const = CHANNELS[channel]
        except KeyError:
            raise ValueError(repr(channel) + ' is an invalid channel type'
                             '; see wand.image.CHANNELS dictionary')
        try:
            op =  COMPOSITE_OPERATORS.index(operator)
        except IndexError:
            raise IndexError(repr(operator) + ' is an invalid composite '
                             'operator type; see wand.image.COMPOSITE_'
                             'OPERATORS dictionary')
        library.MagickCompositeImageChannel(self.wand, ch_const, image.wand,
                                            op, int(left), int(top))
        self.raise_exception()

    @manipulative
    def modulate(self, brightness=100.0, saturation=100.0, hue=100.0):
        """Changes the brightness, saturation and hue of an image.
        We modulate the image with the given ``brightness``, ``saturation``
        and ``hue``.

        :param brightness: percentage of brightness
        :type brightness: :class:`numbers.Real`
        :param saturation: percentage of saturation
        :type saturation: :class:`numbers.Real`
        :param hue: percentage of hue rotation
        :type hue: :class:`numbers.Real`

        :raises exceptions.ValueError:
           when one or more arguments are invalid
        
        .. versionadded:: 0.3.4

        """
        if not isinstance(brightness, numbers.Real):
            raise TypeError('brightness has to be a numbers.Real, not ' +
                            repr(brightness))

        elif not isinstance(saturation, numbers.Real):
            raise TypeError('saturation has to be a numbers.Real, not ' +
                            repr(saturation))

        elif not isinstance(hue, numbers.Real):
            raise TypeError('hue has to be a numbers.Real, not '+
                            repr(hue))
        r = library.MagickModulateImage(
            self.wand,
            ctypes.c_double(brightness),
            ctypes.c_double(saturation),
            ctypes.c_double(hue)
        )
        if not r:
            self.raise_exception()

    @manipulative
    def gaussian_blur(self, radius, sigma):
        """Blurs the image.  We convolve the image with a gaussian operator
        of the given ``radius`` and standard deviation (``sigma``).
        For reasonable results, the ``radius`` should be larger
        than ``sigma``.  Use a ``radius`` of 0 and :meth:`blur()` selects
        a suitable ``radius`` for you.

        :param radius: the radius of the, in pixels,
                       not counting the center pixel
        :type radius: :class:`numbers.Real`
        :param sigma: the standard deviation of the, in pixels
        :type sigma: :class:`numbers.Real`

        .. versionadded:: 0.3.3

        """
        if not isinstance(radius, numbers.Real):
            raise TypeError('radius has to be a numbers.Real, not ' +
                            repr(radius))
        elif not isinstance(sigma, numbers.Real):
            raise TypeError('sigma has to be a numbers.Real, not ' +
                            repr(sigma))
        r = library.MagickGaussianBlurImage(self.wand, radius, sigma)
        if not r:
            self.raise_exception()

    @manipulative
    def unsharp_mask(self, radius, sigma, amount, threshold):
        """Sharpens the image using unsharp mask filter. We convolve the image
        with a Gaussian operator of the given ``radius`` and standard deviation
        (``sigma``). For reasonable results, ``radius`` should be larger than
        ``sigma``. Use a radius of 0 and :meth:`unsharp_mask()`` selects
        a suitable radius for you.

        :param radius: the radius of the Gaussian, in pixels,
                       not counting the center pixel
        :type radius: :class:`numbers.Real`
        :param sigma: the standard deviation of the Gaussian, in pixels
        :type sigma: :class:`numbers.Real`
        :param amount: the percentage of the difference between the original
                       and the blur image that is added back into the original
        :type amount: :class:`numbers.Real`
        :param threshold: the threshold in pixels needed to apply
                          the diffence amount
        :type threshold: :class:`numbers.Real`

        .. versionadded:: 0.3.4

        """
        if not isinstance(radius, numbers.Real):
            raise TypeError('radius has to be a numbers.Real, not ' +
                            repr(radius))
        elif not isinstance(sigma, numbers.Real):
            raise TypeError('sigma has to be a numbers.Real, not ' +
                            repr(sigma))
        elif not isinstance(amount, numbers.Real):
            raise TypeError('amount has to be a numbers.Real, not ' +
                            repr(amount))
        elif not isinstance(threshold, numbers.Real):
            raise TypeError('threshold has to be a numbers.Real, not ' +
                            repr(threshold))
        r = library.MagickUnsharpMaskImage(self.wand, radius, sigma,
                                           amount, threshold)
        if not r:
            self.raise_exception()

    @manipulative
    def watermark(self, image, transparency=0.0, left=0, top=0):
        """Transparentized the supplied ``image`` and places it over the
        current image, with the top left corner of ``image`` at coordinates
        ``left``, ``top`` of the current image.  The dimensions of the
        current image are not changed.

        :param image: the image placed over the current image
        :type image: :class:`wand.image.Image`
        :param transparency: the percentage fade that should be performed on
                             the image, from 0.0 to 1.0
        :type transparency: :class:`numbers.Real`
        :param left: the x-coordinate where `image` will be placed
        :type left: :class:`numbers.Integral`
        :param top: the y-coordinate where `image` will be placed
        :type top: :class:`numbers.Integral`

        .. versionadded:: 0.2.0

        """
        with image.clone() as watermark_image:
            watermark_image.transparentize(transparency)
            self.composite(watermark_image, left=left, top=top)
        self.raise_exception()

    def __repr__(self):
        cls = type(self)
        if getattr(self, 'c_resource', None) is None:
            return '<{0}.{1}: (closed)>'.format(cls.__module__, cls.__name__)
        return '<{0}.{1}: {2} ({3}x{4})>'.format(
            cls.__module__, cls.__name__,
            self.signature[:7], self.width, self.height
        )


class Image(BaseImage):
    """An image object.

    :param image: makes an exact copy of the ``image``
    :type image: :class:`Image`
    :param blob: opens an image of the ``blob`` byte array
    :type blob: :class:`str`
    :param file: opens an image of the ``file`` object
    :type file: file object
    :param filename: opens an image of the ``filename`` string
    :type filename: :class:`basestring`
    :param format: forces filename to  buffer.``format`` to help
                   imagemagick detect the file format. Used only in
                   ``blob`` or ``file`` cases
    :type format: :class:`basestring`
    :param width: the width of new blank image.
    :type width: :class:`numbers.Integral`
    :param height: the height of new blank imgage.
    :type height: :class:`numbers.Integral`
    :param background: an optional background color.
                       default is transparent
    :type background: :class:`wand.color.Color`
    :param resolution: set a resolution value (dpi),
        usefull for vectorial formats (like pdf)
    :type resolution: :class:`collections.Sequence`,
                      :Class:`numbers.Integral`

    .. versionadded:: 0.1.5
       The ``file`` parameter.

    .. versionadded:: 0.1.1
       The ``blob`` parameter.

    .. versionadded:: 0.2.1
       The ``format`` parameter.

    .. versionadded:: 0.2.2
       The ``width``, ``height``, ``background`` parameters.

    .. versionadded:: 0.3.0
       The ``resolution`` parameter.

    .. describe:: [left:right, top:bottom]

       Crops the image by its ``left``, ``right``, ``top`` and ``bottom``,
       and then returns the cropped one. ::

           with img[100:200, 150:300] as cropped:
               # manipulated the cropped image
               pass

       Like other subscriptable objects, default is 0 or its width/height::

           img[:, :]        #--> just clone
           img[:100, 200:]  #--> equivalent to img[0:100, 200:img.height]

       Negative integers count from the end (width/height)::

           img[-70:-50, -20:-10]
           #--> equivalent to img[width-70:width-50, height-20:height-10]

       :returns: the cropped image
       :rtype: :class:`Image`

       .. versionadded:: 0.1.2

    """

    #: (:class:`Metadata`) The metadata mapping of the image.  Read only.
    #:
    #: .. versionadded:: 0.3.0
    metadata = None

    #: (:class:`ChannelImageDict`) The mapping of separated channels
    #: from the image. ::
    #:
    #:     with image.channel_images['red'] as red_image:
    #:         display(red_image)
    channel_images = None

    #: (:class:`ChannelDepthDict`) The mapping of channels to their depth.
    #: Read only.
    #:
    #: .. versionadded:: 0.3.0
    channel_depths = None

    def __init__(self, image=None, blob=None, file=None, filename=None,
                 format=None, width=None, height=None, background=None,
                 resolution=None):
        new_args = width, height, background
        open_args = image, blob, file, filename
        if (any(a is not None for a in new_args) and
            any(a is not None for a in open_args)):
            raise TypeError('blank image parameters cant be used with image '
                            'opening parameters')
        elif any(a is not None and b is not None
                 for i, a in enumerate(open_args)
                 for b in open_args[:i] + open_args[i + 1:]):
            raise TypeError('parameters are exclusive each other; use only '
                            'one at once')
        elif not (format is None or isinstance(format, string_type)):
            raise TypeError('format must be a string, not ' + repr(format))
        with self.allocate():
            if image is None:
                wand = library.NewMagickWand()
                super(Image, self).__init__(wand)
            if width is not None and height is not None:
                self.blank(width, height, background)
            elif image is not None:
                if not isinstance(image, BaseImage):
                    raise TypeError('image must be a wand.image.Image '
                                    'instance, not ' + repr(image))
                elif format:
                    raise TypeError('format option cannot be used with image '
                                    'nor filename')
                wand = library.CloneMagickWand(image.wand)
                super(Image, self).__init__(wand)
            else:
                if format:
                    format = binary(format)
                if file is not None:
                    if format:
                        library.MagickSetFilename(self.wand,
                                                  b'buffer.' + format)
                    self.read(file=file, resolution=resolution)
                if blob is not None:
                    if format:
                        library.MagickSetFilename(self.wand,
                                                  b'buffer.' + format)
                    self.read(blob=blob, resolution=resolution)
                elif filename is not None:
                    if format:
                        raise TypeError(
                            'format option cannot be used with image '
                            'nor filename'
                        )
                    self.read(filename=filename, resolution=resolution)
            self.metadata = Metadata(self)
            from .sequence import Sequence
            self.sequence = Sequence(self)
        self.raise_exception()

    def read(self, file=None, filename=None, blob=None, resolution=None):
        """Read new image into Image() object.

        :param blob: reads an image from the ``blob`` byte array
        :type blob: :class:`str`
        :param file: reads an image from the ``file`` object
        :type file: file object
        :param filename: reads an image from the ``filename`` string
        :type filename: :class:`basestring`
        :param resolution: set a resolution value (DPI),
                           usefull for vectorial formats (like PDF)
        :type resolution: :class:`collections.Sequence`,
                          :class:`numbers.Integral`

        .. versionadded:: 0.3.0

        """
        # Resolution must be set after image reading.
        if resolution is not None:
            if (isinstance(resolution, collections.Sequence) and
                len(resolution) == 2):
                library.MagickSetResolution(self.wand, *resolution)
            elif isinstance(resolution, numbers.Integral):
                library.MagickSetResolution(self.wand, resolution, resolution)
            else:
                raise TypeError('resolution must be a (x, y) pair or an '
                                'integer of the same x/y')
        if file is not None:
            if (isinstance(file, file_types) and
                hasattr(libc, 'fdopen')):
                fd = libc.fdopen(file.fileno(), file.mode)
                r = library.MagickReadImageFile(self.wand, fd)
            elif not callable(getattr(file, 'read', None)):
                raise TypeError('file must be a readable file object'
                                ', but the given object does not '
                                'have read() method')
            else:
                blob = file.read()
                file = None
        if blob is not None:
            if not isinstance(blob, collections.Iterable):
                raise TypeError('blob must be iterable, not ' +
                                repr(blob))
            if not isinstance(blob, binary_type):
                blob = b''.join(blob)
            r = library.MagickReadImageBlob(self.wand, blob, len(blob))
        elif filename is not None:
            filename = encode_filename(filename)
            r = library.MagickReadImage(self.wand, filename)
        if not r:
            self.raise_exception()

    def close(self):
        """Closes the image explicitly. If you use the image object in
        :keyword:`with` statement, it was called implicitly so don't have to
        call it.

        .. note::

           It has the same functionality of :attr:`destroy()` method.

        """
        self.destroy()

    def clear(self):
        """Clears resources associated with the image, leaving the image blank,
        and ready to be used with new image.

        .. versionadded:: 0.3.0

        """
        library.ClearMagickWand(self.wand)

    @property
    def format(self):
        """(:class:`basestring`) The image format.

        If you want to convert the image format, just reset this property::

            assert isinstance(img, wand.image.Image)
            img.format = 'png'

        It may raise :exc:`ValueError` when the format is unsupported.

        .. seealso::

           `ImageMagick Image Formats`__
              ImageMagick uses an ASCII string known as *magick* (e.g. ``GIF``)
              to identify file formats, algorithms acting as formats,
              built-in patterns, and embedded profile types.

           __ http://www.imagemagick.org/script/formats.php

        .. versionadded:: 0.1.6

        """
        fmt = library.MagickGetImageFormat(self.wand)
        if bool(fmt):
            return text(fmt.value)
        self.raise_exception()

    @format.setter
    def format(self, fmt):
        if not isinstance(fmt, string_type):
            raise TypeError("format must be a string like 'png' or 'jpeg'"
                            ', not ' + repr(fmt))
        fmt = fmt.strip()
        r = library.MagickSetImageFormat(self.wand, binary(fmt.upper()))
        if not r:
            raise ValueError(repr(fmt) + ' is unsupported format')
        r = library.MagickSetFilename(self.wand,
                                      b'buffer.' + binary(fmt.lower()))
        if not r:
            self.raise_exception()

    @property
    def mimetype(self):
        """(:class:`basestring`) The MIME type of the image
        e.g. ``'image/jpeg'``, ``'image/png'``.

        .. versionadded:: 0.1.7

        """
        rp = libmagick.MagickToMime(binary(self.format))
        if not bool(rp):
            self.raise_exception()
        mimetype = rp.value
        return text(mimetype)

    @property
    def animation(self):
        return self.mimetype == 'image/gif' and len(self.sequence) > 1

    def blank(self, width, height, background=None):
        """Creates blank image.

        :param width: the width of new blank image.
        :type width: :class:`numbers.Integral`
        :param height: the height of new blank imgage.
        :type height: :class:`numbers.Integral`
        :param background: an optional background color.
                           default is transparent
        :type background: :class:`wand.color.Color`
        :returns: blank image
        :rtype: :class:`Image`

        .. versionadded:: 0.3.0

        """
        if not isinstance(width, numbers.Integral) or width < 1:
            raise TypeError('width must be a natural number, not ' +
                            repr(width))
        if not isinstance(height, numbers.Integral) or height < 1:
            raise TypeError('height must be a natural number, not ' +
                            repr(height))
        if background is not None and not isinstance(background, Color):
            raise TypeError('background must be a wand.color.Color '
                            'instance, not ' + repr(background))
        if background is None:
            background = Color('transparent')
        with background:
            r = library.MagickNewImage(self.wand, width, height,
                                   background.resource)
            if not r:
                self.raise_exception()
        return self

    def convert(self, format):
        """Converts the image format with the original image maintained.
        It returns a converted image instance which is new. ::

            with img.convert('png') as converted:
                converted.save(filename='converted.png')

        :param format: image format to convert to
        :type format: :class:`basestring`
        :returns: a converted image
        :rtype: :class:`Image`
        :raises: :exc:`ValueError` when the given ``format`` is unsupported

        .. versionadded:: 0.1.6

        """
        cloned = self.clone()
        cloned.format = format
        return cloned

    def save(self, file=None, filename=None):
        """Saves the image into the ``file`` or ``filename``. It takes
        only one argument at a time.

        :param file: a file object to write to
        :type file: file object
        :param filename: a filename string to write to
        :type filename: :class:`basename`

        .. versionadded:: 0.1.5
           The ``file`` parameter.

        .. versionadded:: 0.1.1

        """
        if file is None and filename is None:
            raise TypeError('expected an argument')
        elif file is not None and filename is not None:
            raise TypeError('expected only one argument; but two passed')
        elif file is not None:
            if isinstance(file, string_type):
                raise TypeError('file must be a writable file object, '
                                'but {0!r} is a string; did you want '
                                '.save(filename={0!r})?'.format(file))
            elif isinstance(file, file_types) and hasattr(libc, 'fdopen'):
                fd = libc.fdopen(file.fileno(), file.mode)
                if len(self.sequence) > 1:
                    r = library.MagickWriteImagesFile(self.wand, fd)
                else:
                    r = library.MagickWriteImageFile(self.wand, fd)
                libc.fflush(fd)
                if not r:
                    self.raise_exception()
            else:
                if not callable(getattr(file, 'write', None)):
                    raise TypeError('file must be a writable file object, '
                                    'but it does not have write() method: ' +
                                    repr(file))
                file.write(self.make_blob())
        else:
            if not isinstance(filename, string_type):
                raise TypeError('filename must be a string, not ' +
                                repr(filename))
            filename = encode_filename(filename)
            if len(self.sequence) > 1:
                r = library.MagickWriteImages(self.wand, filename, True)
            else:
                r = library.MagickWriteImage(self.wand, filename)
            if not r:
                self.raise_exception()

    def make_blob(self, format=None):
        """Makes the binary string of the image.

        :param format: the image format to write e.g. ``'png'``, ``'jpeg'``.
                       it is omittable
        :type format: :class:`basestring`
        :returns: a blob (bytes) string
        :rtype: :class:`str`
        :raises: :exc:`ValueError` when ``format`` is invalid

        .. versionchanged:: 0.1.6
           Removed a side effect that changes the image :attr:`format`
           silently.

        .. versionadded:: 0.1.5
           The ``format`` parameter became optional.

        .. versionadded:: 0.1.1

        """
        if format is not None:
            with self.convert(format) as converted:
                return converted.make_blob()
        library.MagickResetIterator(self.wand)
        length = ctypes.c_size_t()
        blob_p = None
        if len(self.sequence) > 1:
            blob_p = library.MagickGetImagesBlob(self.wand,
                                                 ctypes.byref(length))
        else:
            blob_p = library.MagickGetImageBlob(self.wand, ctypes.byref(length))
        if blob_p and length.value:
            blob = ctypes.string_at(blob_p, length.value)
            library.MagickRelinquishMemory(blob_p)
            return blob
        self.raise_exception()

    def strip(self):
        """Strips an image of all profiles and comments.

        .. versionadded:: 0.2.0

        """
        result = library.MagickStripImage(self.wand)
        if not result:
            self.raise_exception()

    def trim(self, color=None, fuzz=0):
        """Remove solid border from image. Uses top left pixel as a guide
        by default, or you can also specify the ``color`` to remove.

        :param color: the border color to remove.
                      if it's omitted top left pixel is used by default
        :type color: :class:`~wand.color.Color`
        :param fuzz: Defines how much tolerance is acceptable to consider
                     two colors as the same.
        :type fuzz: :class:`numbers.Integral`

        .. versionadded:: 0.3.0
           Optional ``color`` and ``fuzz`` parameters.

        .. versionadded:: 0.2.1

        """
        with color or self[0, 0] as color:
            self.border(color, 1, 1)
        result = library.MagickTrimImage(self.wand, fuzz)
        if not result:
            self.raise_exception()

    def border(self, color, width, height):
        """Surrounds the image with a border.

        :param bordercolor: the border color pixel wand
        :type image: :class:`~wand.color.Color`
        :param width: the border width
        :type width: :class:`numbers.Integral`
        :param height: the border height
        :type height: :class:`numbers.Integral`

        .. versionadded:: 0.3.0

        """
        if not isinstance(color, Color):
            raise TypeError('color must be a wand.color.Color object, not ' +
                            repr(color))
        with color:
            result = library.MagickBorderImage(self.wand, color.resource,
                                               width, height)
        if not result:
            self.raise_exception()

    def normalize(self, channel=None):
        """Normalize color channels.

        :param channel: the channel type.  available values can be found
                        in the :const:`CHANNELS` mapping.  If ``None``,
                        normalize all channels.
        :type channel: :class:`basestring`

        """
        if channel:
            try:
                ch_const = CHANNELS[channel]
            except KeyError:
                raise ValueError(repr(channel) + ' is an invalid channel type'
                                 '; see wand.image.CHANNELS dictionary')
            r = library.MagickNormalizeImageChannel(self.wand, ch_const)
        else:
            r = library.MagickNormalizeImage(self.wand)
        if not r:
            self.raise_exception()

    def _repr_png_(self):
        with self.convert('png') as cloned:
            return cloned.make_blob()

    def __repr__(self):
        cls = type(self)
        if getattr(self, 'c_resource', None) is None:
            return '<{0}.{1}: (closed)>'.format(cls.__module__, cls.__name__)
        return '<{0}.{1}: {2} {3!r} ({4}x{5})>'.format(
            cls.__module__, cls.__name__,
            self.signature[:7], self.format, self.width, self.height
        )


class Iterator(Resource, collections.Iterator):
    """Row iterator for :class:`Image`. It shouldn't be instantiated
    directly; instead, it can be acquired through :class:`Image` instance::

        assert isinstance(image, wand.image.Image)
        iterator = iter(image)

    It doesn't iterate every pixel, but rows. For example::

        for row in image:
            for col in row:
                assert isinstance(col, wand.color.Color)
                print(col)

    Every row is a :class:`collections.Sequence` which consists of
    one or more :class:`wand.color.Color` values.

    :param image: the image to get an iterator
    :type image: :class:`Image`

    .. versionadded:: 0.1.3

    """

    c_is_resource = library.IsPixelIterator
    c_destroy_resource = library.DestroyPixelIterator
    c_get_exception = library.PixelGetIteratorException
    c_clear_exception = library.PixelClearIteratorException

    def __init__(self, image=None, iterator=None):
        if image is not None and iterator is not None:
            raise TypeError('it takes only one argument at a time')
        with self.allocate():
            if image is not None:
                if not isinstance(image, Image):
                    raise TypeError('expected a wand.image.Image instance, '
                                    'not ' + repr(image))
                self.resource = library.NewPixelIterator(image.wand)
                self.height = image.height
            else:
                if not isinstance(iterator, Iterator):
                    raise TypeError('expected a wand.image.Iterator instance, '
                                    'not ' + repr(iterator))
                self.resource = library.ClonePixelIterator(iterator.resource)
                self.height = iterator.height
        self.raise_exception()
        self.cursor = 0

    def __iter__(self):
        return self

    def seek(self, y):
        if not isinstance(y, numbers.Integral):
            raise TypeError('expected an integer, but got ' + repr(y))
        elif y < 0:
            raise ValueError('cannot be less than 0, but got ' + repr(y))
        elif y > self.height:
            raise ValueError('canot be greater than height')
        self.cursor = y
        if y == 0:
            library.PixelSetFirstIteratorRow(self.resource)
        else:
            if not library.PixelSetIteratorRow(self.resource, y - 1):
                self.raise_exception()

    def __next__(self, x=None):
        if self.cursor >= self.height:
            self.destroy()
            raise StopIteration()
        self.cursor += 1
        width = ctypes.c_size_t()
        pixels = library.PixelGetNextIteratorRow(self.resource,
                                                 ctypes.byref(width))
        get_color = library.PixelGetMagickColor
        struct_size = ctypes.sizeof(MagickPixelPacket)
        if x is None:
            r_pixels = [None] * width.value
            for x in xrange(width.value):
                pc = pixels[x]
                packet_buffer = ctypes.create_string_buffer(struct_size)
                get_color(pc, packet_buffer)
                r_pixels[x] = Color(raw=packet_buffer)
            return r_pixels
        packet_buffer = ctypes.create_string_buffer(struct_size)
        get_color(pixels[x], packet_buffer)
        return Color(raw=packet_buffer)

    next = __next__  # Python 2 compatibility

    def clone(self):
        """Clones the same iterator.

        """
        return type(self)(iterator=self)


class ImageProperty(object):
    """The mixin class to maintain a weak reference to the parent
    :class:`Image` object.

    .. versionadded:: 0.3.0

    """

    def __init__(self, image):
        if not isinstance(image, BaseImage):
            raise TypeError('expected a wand.image.BaseImage instance, '
                            'not ' + repr(image))
        self._image = weakref.ref(image)

    @property
    def image(self):
        """(:class:`Image`) The parent image.

        It ensures that the parent :class:`Image`, which is held in a weak
        reference, still exists.  Returns the dereferenced :class:`Image`
        if it does exist, or raises a :exc:`ClosedImageError` otherwise.

        :exc: `ClosedImageError` when the parent Image has been destroyed

        """
        # Dereference our weakref and check that the parent Image stil exists
        image = self._image()
        if image is not None:
            return image
        raise ClosedImageError(
            'parent Image of {0!r} has been destroyed'.format(self)
        )

class OptionDict(ImageProperty, collections.MutableMapping):
    """Mutable mapping of the image internal options.  See available
    options in :const:`OPTIONS` constant.

    .. versionadded:: 0.3.0

    """

    def __iter__(self):
        return iter(OPTIONS)

    def __len__(self):
        return len(OPTIONS)

    def __getitem__(self, key):
        if not isinstance(key, string_type):
            raise TypeError('option name must be a string, not ' + repr(key))
        if key not in OPTIONS:
            raise ValueError('invalid option: ' + repr(key))
        image = self.image
        return text(library.MagickGetOption(image.wand, binary(key)))

    def __setitem__(self, key, value):
        if not isinstance(key, string_type):
            raise TypeError('option name must be a string, not ' + repr(key))
        if not isinstance(value, string_type):
            raise TypeError('option value must be a string, not ' +
                            repr(value))
        if key not in OPTIONS:
            raise ValueError('invalid option: ' + repr(key))
        image = self.image
        library.MagickSetOption(image.wand, binary(key), binary(value))

    def __delitem__(self, key):
        self[key] = ''


class Metadata(ImageProperty, collections.Mapping):
    """Class that implements dict-like read-only access to image metadata
    like EXIF or IPTC headers.

    :param image: an image instance
    :type image: :class:`Image`

    .. note::

       You don't have to use this by yourself.
       Use :attr:`Image.metadata` property instead.

    .. versionadded:: 0.3.0

    """

    def __init__(self, image):
        if not isinstance(image, Image):
            raise TypeError('expected a wand.image.Image instance, '
                            'not ' + repr(image))
        super(Metadata, self).__init__(image)

    def __getitem__(self, k):
        """
        :param k: Metadata header name string.
        :type k: :class:`basestring`
        :returns: a header value string
        :rtype: :class:`str`
        """
        image = self.image
        if not isinstance(k, string_type):
            raise TypeError('k must be a string, not ' + repr(k))
        v = library.MagickGetImageProperty(image.wand, binary(k))
        if bool(v) is False:
            raise KeyError(k)
        value = v.value
        return text(value)

    def __iter__(self):
        image = self.image
        num = ctypes.c_size_t()
        props_p = library.MagickGetImageProperties(image.wand, b'', num)
        props = [text(props_p[i]) for i in xrange(num.value)]
        library.MagickRelinquishMemory(props_p)
        return iter(props)

    def __len__(self):
        image = self.image
        num = ctypes.c_size_t()
        props_p = library.MagickGetImageProperties(image.wand, b'', num)
        library.MagickRelinquishMemory(props_p)
        return num.value


class ChannelImageDict(ImageProperty, collections.Mapping):
    """The mapping table of separated images of the particular channel
    from the image.

    :param image: an image instance
    :type image: :class:`Image`

    .. note::

       You don't have to use this by yourself.
       Use :attr:`Image.channel_images` property instead.

    .. versionadded:: 0.3.0

    """

    def __iter__(self):
        return iter(CHANNELS)

    def __len__(self):
        return len(CHANNELS)

    def __getitem__(self, channel):
        c = CHANNELS[channel]
        img = self.image.clone()
        succeeded = library.MagickSeparateImageChannel(img.wand, c)
        if not succeeded:
            try:
                img.raise_exception()
            except WandException:
                img.close()
                raise
        return img


class ChannelDepthDict(ImageProperty, collections.Mapping):
    """The mapping table of channels to their depth.

    :param image: an image instance
    :type image: :class:`Image`

    .. note::

       You don't have to use this by yourself.
       Use :attr:`Image.channel_depths` property instead.

    .. versionadded:: 0.3.0

    """

    def __iter__(self):
        return iter(CHANNELS)

    def __len__(self):
        return len(CHANNELS)

    def __getitem__(self, channel):
        c = CHANNELS[channel]
        depth = library.MagickGetImageChannelDepth(self.image.wand, c)
        return int(depth)


class HistogramDict(collections.Mapping):
    """Specialized mapping object to represent color histogram.
    Keys are colors, and values are the number of pixels.

    :param image: the image to get its histogram
    :type image: :class:`BaseImage`

    .. versionadded:: 0.3.0

    """

    def __init__(self, image):
        self.size = ctypes.c_size_t()
        self.pixels = library.MagickGetImageHistogram(
            image.wand,
            ctypes.byref(self.size)
        )
        self.counts = None

    def __len__(self):
        if self.counts is None:
            return self.size.value
        return len(self.counts)

    def __iter__(self):
        if self.counts is None:
            pixels = self.pixels
            string = library.PixelGetColorAsString
            return (Color(string(pixels[i]).value)
                    for i in xrange(self.size.value))
        return iter(Color(string=c) for c in self.counts)

    def __getitem__(self, color):
        if self.counts is None:
            string = library.PixelGetColorAsNormalizedString
            pixels = self.pixels
            count = library.PixelGetColorCount
            self.counts = dict(
                (text(string(pixels[i]).value), count(pixels[i]))
                for i in xrange(self.size.value)
            )
            del self.size, self.pixels
        return self.counts[color.normalized_string]


class ClosedImageError(DestroyedResourceError):
    """An error that rises when some code tries access to an already closed
    image.

    """