/usr/lib/python2.7/dist-packages/fabio/compression.py is in python-fabio 0.3.0+dfsg-1build1.
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#
# Project: X-ray image reader
# https://github.com/kif/fabio
#
#
# Copyright (C) European Synchrotron Radiation Facility, Grenoble, France
#
# Principal author: Jérôme Kieffer (Jerome.Kieffer@ESRF.eu)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
"""
Authors: Jérôme Kieffer, ESRF
email:jerome.kieffer@esrf.fr
FabIO library containing compression and decompression algorithm for various
"""
# get ready for python3
from __future__ import absolute_import, print_function, with_statement, division
__author__ = "Jérôme Kieffer"
__contact__ = "jerome.kieffer@esrf.eu"
__license__ = "GPLv3+"
__date__ = "30/10/2015"
__copyright__ = "European Synchrotron Radiation Facility, Grenoble, France"
import sys
import base64
import hashlib
import struct
import logging
logger = logging.getLogger("compression")
from .fabioutils import six
if six.PY2:
bytes = str
import numpy
try:
if sys.version_info < (2, 7):
from .third_party import gzip
else:
import gzip
except ImportError:
logger.error("Unable to import gzip module: disabling gzip compression")
gzip = None
try:
import bz2
except ImportError:
logger.error("Unable to import bz2 module: disabling bz2 compression")
bz2 = None
try:
import zlib
except ImportError:
logger.error("Unable to import zlib module: disabling zlib compression")
zlib = None
def md5sum(blob):
"""
returns the md5sum of an object...
"""
return base64.b64encode(hashlib.md5(blob).digest())
def endianness():
"""
Return the native endianness of the system
"""
if numpy.little_endian:
return "LITTLE_ENDIAN"
else:
return "BIG_ENDIAN"
def decGzip(stream):
"""
Decompress a chunk of data using the gzip algorithm from Python or alternatives if possible
"""
if gzip is None:
raise ImportError("gzip module is not available")
fileobj = six.BytesIO(stream)
try:
rawData = gzip.GzipFile(fileobj=fileobj).read()
except IOError:
logger.warning("Encounter the python-gzip bug with trailing garbage, trying subprocess gzip")
try:
# This is as an ugly hack against a bug in Python gzip
import subprocess
sub = subprocess.Popen(["gzip", "-d", "-f"], stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE)
rawData, err = sub.communicate(input=stream)
logger.debug("Gzip subprocess ended with %s err= %s; I got %s bytes back" % (sub.wait(), err, len(rawData)))
except Exception as error: # IGNORE:W0703
logger.warning("Unable to use the subprocess gzip (%s). Is gzip available? " % error)
for i in range(1, 513):
try:
fileobj = six.BytesIO(stream[:-i])
rawData = gzip.GzipFile(fileobj=fileobj).read()
except IOError:
logger.debug("trying with %s bytes less, doesn't work" % i)
else:
break
else:
logger.error("I am totally unable to read this gzipped compressed data block, giving up")
return rawData
def decBzip2(stream):
"""
Decompress a chunk of data using the bzip2 algorithm from Python
"""
if bz2 is None:
raise ImportError("bz2 module is not available")
return bz2.decompress(stream)
def decZlib(stream):
"""
Decompress a chunk of data using the zlib algorithm from Python
"""
if zlib is None:
raise ImportError("zlib module is not available")
return zlib.decompress(stream)
def decByteOffset_numpy(stream, size=None):
"""
Analyze a stream of char with any length of exception:
2, 4, or 8 bytes integers
@param stream: string representing the compressed data
@param size: the size of the output array (of longInts)
@return: 1D-ndarray
"""
logger.debug("CBF decompression using Numpy")
listnpa = []
key16 = b"\x80"
key32 = b"\x00\x80"
key64 = b"\x00\x00\x00\x80"
shift = 1
while True:
idx = stream.find(key16)
if idx == -1:
listnpa.append(numpy.fromstring(stream, dtype="int8"))
break
listnpa.append(numpy.fromstring(stream[:idx], dtype="int8"))
if stream[idx + 1:idx + 3] == key32:
if stream[idx + 3:idx + 7] == key64:
# 64 bits int
res = numpy.fromstring(stream[idx + 7:idx + 15], dtype="int64")
listnpa.append(res)
shift = 15
else:
# 32 bits int
res = numpy.fromstring(stream[idx + 3:idx + 7], dtype="int32")
listnpa.append(res)
shift = 7
else: # int16
res = numpy.fromstring(stream[idx + 1:idx + 3], dtype="int16")
listnpa.append(res)
shift = 3
stream = stream[idx + shift:]
if not numpy.little_endian:
for res in listnpa:
if res.dtype != numpy.int8:
res.byteswap(True)
return (numpy.hstack(listnpa)).astype("int64").cumsum()
def decByteOffset_cython(stream, size=None):
"""
Analyze a stream of char with any length of exception:
2, 4, or 8 bytes integers
@param stream: string representing the compressed data
@param size: the size of the output array (of longInts)
@return: 1D-ndarray
"""
logger.debug("CBF decompression using cython")
try:
from .byte_offset import analyseCython
except ImportError as error:
logger.error("Failed to import byte_offset cython module, falling back on numpy method")
return decByteOffset_numpy(stream, size)
else:
return analyseCython(stream, size)
decByteOffset = decByteOffset_cython
def compByteOffset_numpy(data):
"""
Compress a dataset into a string using the byte_offet algorithm
@param data: ndarray
@return: string/bytes with compressed data
test = numpy.array([0,1,2,127,0,1,2,128,0,1,2,32767,0,1,2,32768,0,1,2,2147483647,0,1,2,2147483648,0,1,2,128,129,130,32767,32768,128,129,130,32768,2147483647,2147483648])
"""
flat = data.astype("int64").ravel()
delta = numpy.zeros_like(flat)
delta[0] = flat[0]
delta[1:] = flat[1:] - flat[:-1]
mask = ((delta > 127) + (delta < -127))
exceptions = numpy.nonzero(mask)[0]
if numpy.little_endian:
byteswap = False
else:
byteswap = True
start = 0
binary_blob = b""
for stop in exceptions:
if stop - start > 0:
binary_blob += delta[start:stop].astype("int8").tostring()
exc = delta[stop]
if (exc > 2147483647) or (exc < -2147483647): # 2**31-1
binary_blob += b"\x80\x00\x80\x00\x00\x00\x80"
if byteswap:
binary_blob += delta[stop:stop + 1].byteswap().tostring()
else:
binary_blob += delta[stop:stop + 1].tostring()
elif (exc > 32767) or (exc < -32767): # 2**15-1
binary_blob += b"\x80\x00\x80"
if byteswap:
binary_blob += delta[stop:stop + 1].astype("int32").byteswap().tostring()
else:
binary_blob += delta[stop:stop + 1].astype("int32").tostring()
else: # >127
binary_blob += b"\x80"
if byteswap:
binary_blob += delta[stop:stop + 1].astype("int16").byteswap().tostring()
else:
binary_blob += delta[stop:stop + 1].astype("int16").tostring()
start = stop + 1
if start < delta.size:
binary_blob += delta[start:].astype("int8").tostring()
return binary_blob
compByteOffset = compByteOffset_numpy
def decTY1(raw_8, raw_16=None, raw_32=None):
"""
Modified byte offset decompressor used in Oxford Diffraction images
Note: Always expect little endian data on the disk
@param raw_8: strings containing raw data with integer 8 bits
@param raw_16: strings containing raw data with integer 16 bits
@param raw_32: strings containing raw data with integer 32 bits
@return: numpy.ndarray
"""
data = numpy.fromstring(raw_8, dtype="uint8").astype(int)
data -= 127
if raw_32 is not None:
int32 = numpy.fromstring(raw_32, dtype="int32")
if not numpy.little_endian:
int32.byteswap(True)
exception32 = numpy.nonzero(data == 128)
if raw_16 is not None:
int16 = numpy.fromstring(raw_16, dtype="int16")
if not numpy.little_endian:
int16.byteswap(True)
exception16 = numpy.nonzero(data == 127)
data[exception16] = int16
if raw_32:
data[exception32] = int32
summed = data.cumsum()
smax = summed.max()
if (smax > (2 ** 31 - 1)):
bytecode = "int64"
elif (smax > (2 ** 15 - 1)):
bytecode = "int32"
elif (smax > (2 ** 7 - 1)):
bytecode = "int16"
else:
bytecode = "int8"
return summed.astype(bytecode)
decKM4CCD = decTY1
def compTY1(data):
"""
Modified byte offset compressor used in Oxford Diffraction images
@param data: numpy.ndarray with the input data (integers!)
@return: 3-tuple of strings: raw_8,raw_16,raw_32 containing raw data with integer of the given size
"""
fdata = data.ravel()
diff = numpy.zeros_like(fdata)
diff[0] = fdata[0]
diff[1:] = fdata[1:] - fdata[:-1]
adiff = abs(diff)
exception32 = (adiff > (1 << 15) - 1)
exception16 = (adiff >= (1 << 7) - 1) ^ exception32
we16 = numpy.where(exception16)
we32 = numpy.where(exception32)
data_16 = diff[we16].astype(numpy.int16)
data_32 = diff[we32].astype(numpy.int32)
if not numpy.little_endian:
data_16.byteswap(True)
data_32.byteswap(True)
diff[we16] = 127
diff[we32] = 128
diff += 127
data_8 = diff.astype(numpy.uint8)
return data_8.tostring(), data_16.tostring(), data_32.tostring()
def decPCK(stream, dim1=None, dim2=None, overflowPix=None, version=None, normal_start=None, swap_needed=None):
"""
Modified CCP4 pck decompressor used in MAR345 images
@param raw: input string (bytes in python3)
@param dim1,dim2: optional parameters size
@param overflowPix: optional parameters: number of overflowed pixels
@param version: PCK version 1 or 2
@param normal_start: position of the normal value section (can be auto-guessed)
@param swap_needed: set to True when reading data from a foreign endianness (little on big or big on little)
@return : ndarray of 2D with the right size
"""
try:
from .mar345_IO import uncompress_pck
except ImportError as error:
raise RuntimeError("Unable to import mar345_IO to read compressed dataset")
if "seek" in dir(stream):
stream.seek(0)
raw = stream.read()
else:
raw = bytes(stream)
return uncompress_pck(raw, dim1, dim2, overflowPix, version, normal_start, swap_needed)
def compPCK(data):
"""
Modified CCP4 pck compressor used in MAR345 images
@param data: numpy.ndarray (square array)
@return: compressed stream
"""
try:
from .mar345_IO import compress_pck
except ImportError as error:
raise RuntimeError("Unable to import mar345_IO to write compressed dataset")
return compress_pck(data)
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