/usr/share/octave/packages/image-2.2.2/imremap.m is in octave-image 2.2.2-1.
This file is owned by root:root, with mode 0o644.
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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 | ## Copyright (C) 2006 Søren Hauberg <soren@hauberg.org>
##
## 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/>.
## -*- texinfo -*-
## @deftypefn {Function File} @var{warped} = imremap(@var{im}, @var{XI}, @var{YI})
## @deftypefnx{Function File} @var{warped} = imremap(@var{im}, @var{XI}, @var{YI}, @var{interp}, @var{extrapval})
## @deftypefnx{Function File} [@var{warped}, @var{valid} ] = imremap(@dots{})
## Applies any geometric transformation to the image @var{im}.
##
## The arguments @var{XI} and @var{YI} are lookup tables that define the resulting
## image
## @example
## @var{warped}(y,x) = @var{im}(@var{YI}(y,x), @var{XI}(y,x))
## @end example
## where @var{im} is assumed to be a continuous function, which is achieved
## by interpolation. Note that the image @var{im} is expressed in a (X, Y)-coordinate
## system and not a (row, column) system.
##
## The optional argument @var{method} defines the interpolation method to be
## used. All methods supported by @code{interp2} can be used. By default, the
## @code{linear} method is used.
##
## For @sc{matlab} compatibility, the methods @code{bicubic} (same as
## @code{cubic}), @code{bilinear} and @code{triangle} (both the same as
## @code{linear}) are also supported.
##
## All values of the result that fall outside the original image will
## be set to @var{extrapval}. For images of class @code{double} @var{extrapval}
## defaults to @code{NA} and for other classes it defaults to 0.
##
## The optional output @var{valid} is a matrix of the same size as @var{warped}
## that contains the value 1 in pixels where @var{warped} contains an interpolated
## value, and 0 in pixels where @var{warped} contains an extrapolated value.
## @seealso{imperspectivewarp, imrotate, imresize, imshear, interp2}
## @end deftypefn
function [warped, valid] = imremap(im, XI, YI, interp = "linear", extrapval = NA)
if (nargin < 3 || nargin > 5)
print_usage ();
elseif (! isimage (im) || ndims (im) > 3)
error ("imremap: IM must be a grayscale or RGB image.")
elseif (! size_equal (XI, YI) || ! ismatrix (XI) || ndims (XI) != 2)
error ("imremap: XI and YI must be matrices of the same size");
elseif (! ischar (interp))
error ("imremap: INTERP must be a string with interpolation method")
elseif (! isscalar (extrapval))
error ("imremap: EXTRAPVAL must be a scalar");
endif
interp = interp_method (interp);
## Interpolate
if (size (im, 3) == 1) # Gray
warped = grayinterp(im, XI, YI, interp, NA);
else # rgb image
for i = 3:-1:1
warped(:,:,i) = grayinterp(im(:,:,i), XI, YI, interp, NA);
endfor
endif
valid = !isna(warped);
warped(!valid) = extrapval;
## we return image on same class as input
warped = cast (warped, class (im));
endfunction
function [warped, valid] = grayinterp(im, XI, YI, interp, extrapval)
if (strcmp(interp, "cubic"))
warped = graybicubic(double(im), XI, YI, NA);
else
warped = interp2(double(im), XI, YI, interp, NA);
endif
valid = !isna(warped);
warped(!valid) = extrapval;
endfunction
## -*- texinfo -*-
## @deftypefn {Function File} {@var{zi}=} bicubic (@var{x}, @var{y}, @var{z}, @var{xi}, @var{yi})
## Reference:
## Image Processing, Analysis, and Machine Vision, 2nd Ed.
## Sonka et.al.
## Brooks/Cole Publishing Company
## ISBN: 0-534-95393-X
## @seealso{interp2}
## @end deftypefn
function ZI = graybicubic (Z, XI, YI, extrapval = NA)
## Allocate output
[X, Y] = meshgrid(1:columns(Z), 1:rows(Z));
[Zr, Zc] = size(XI);
ZI = zeros(Zr, Zc);
## Find inliers
inside = !( XI < X(1) | XI > X(end) | YI < Y(1) | YI > Y(end) );
## Scale XI and YI to match indices of Z (not needed when interpolating images)
#XI = (columns(Z)-1) * ( XI - X(1) ) / (X(end)-X(1)) + 1;
#YI = (rows(Z)-1) * ( YI - Y(1) ) / (Y(end)-Y(1)) + 1;
## Start the real work
K = floor(XI);
L = floor(YI);
## Coefficients
AY1 = bc((YI-L+1)); AX1 = bc((XI-K+1));
AY0 = bc((YI-L+0)); AX0 = bc((XI-K+0));
AY_1 = bc((YI-L-1)); AX_1 = bc((XI-K-1));
AY_2 = bc((YI-L-2)); AX_2 = bc((XI-K-2));
## Perform interpolation
sz = size(Z);
%ZI(inside) = AY_2 .* AX_2 .* Z(sym_sub2ind(sz, L+2, K+2)) ...
ZI = AY_2 .* AX_2 .* Z(sym_sub2ind(sz, L+2, K+2)) ...
+ AY_2 .* AX_1 .* Z(sym_sub2ind(sz, L+2, K+1)) ...
+ AY_2 .* AX0 .* Z(sym_sub2ind(sz, L+2, K)) ...
+ AY_2 .* AX1 .* Z(sym_sub2ind(sz, L+2, K-1)) ...
+ AY_1 .* AX_2 .* Z(sym_sub2ind(sz, L+1, K+2)) ...
+ AY_1 .* AX_1 .* Z(sym_sub2ind(sz, L+1, K+1)) ...
+ AY_1 .* AX0 .* Z(sym_sub2ind(sz, L+1, K)) ...
+ AY_1 .* AX1 .* Z(sym_sub2ind(sz, L+1, K-1)) ...
+ AY0 .* AX_2 .* Z(sym_sub2ind(sz, L, K+2)) ...
+ AY0 .* AX_1 .* Z(sym_sub2ind(sz, L, K+1)) ...
+ AY0 .* AX0 .* Z(sym_sub2ind(sz, L, K)) ...
+ AY0 .* AX1 .* Z(sym_sub2ind(sz, L, K-1)) ...
+ AY1 .* AX_2 .* Z(sym_sub2ind(sz, L-1, K+2)) ...
+ AY1 .* AX_1 .* Z(sym_sub2ind(sz, L-1, K+1)) ...
+ AY1 .* AX0 .* Z(sym_sub2ind(sz, L-1, K)) ...
+ AY1 .* AX1 .* Z(sym_sub2ind(sz, L-1, K-1));
ZI(!inside) = extrapval;
endfunction
## Checks if data is meshgrided
function b = isgriddata(X)
D = X - repmat(X(1,:), rows(X), 1);
b = all(D(:) == 0);
endfunction
## Checks if data is equally spaced (assumes data is meshgrided)
function b = isequallyspaced(X)
Dx = gradient(X(1,:));
b = all(Dx == Dx(1));
endfunction
## Computes the interpolation coefficients
function o = bc(x)
x = abs(x);
o = zeros(size(x));
idx1 = (x < 1);
idx2 = !idx1 & (x < 2);
o(idx1) = 1 - 2.*x(idx1).^2 + x(idx1).^3;
o(idx2) = 4 - 8.*x(idx2) + 5.*x(idx2).^2 - x(idx2).^3;
endfunction
## This version of sub2ind behaves as if the data was symmetrically padded
function ind = sym_sub2ind(sz, Y, X)
Y(Y<1) = 1 - Y(Y<1);
while (any(Y(:)>2*sz(1)))
Y(Y>2*sz(1)) = round( Y(Y>2*sz(1))/2 );
endwhile
Y(Y>sz(1)) = 1 + 2*sz(1) - Y(Y>sz(1));
X(X<1) = 1 - X(X<1);
while (any(X(:)>2*sz(2)))
X(X>2*sz(2)) = round( X(X>2*sz(2))/2 );
endwhile
X(X>sz(2)) = 1 + 2*sz(2) - X(X>sz(2));
ind = sub2ind(sz, Y, X);
endfunction
%!demo
%! ## Generate a synthetic image and show it
%! I = tril(ones(100)) + abs(rand(100)); I(I>1) = 1;
%! I(20:30, 20:30) = !I(20:30, 20:30);
%! I(70:80, 70:80) = !I(70:80, 70:80);
%! figure, imshow(I);
%! ## Resize the image to the double size and show it
%! [XI, YI] = meshgrid(linspace(1, 100, 200));
%! warped = imremap(I, XI, YI);
%! figure, imshow(warped);
%!demo
%! ## Generate a synthetic image and show it
%! I = tril(ones(100)) + abs(rand(100)); I(I>1) = 1;
%! I(20:30, 20:30) = !I(20:30, 20:30);
%! I(70:80, 70:80) = !I(70:80, 70:80);
%! figure, imshow(I);
%! ## Rotate the image around (0, 0) by -0.4 radians and show it
%! [XI, YI] = meshgrid(1:100);
%! R = [cos(-0.4) sin(-0.4); -sin(-0.4) cos(-0.4)];
%! RXY = [XI(:), YI(:)] * R;
%! XI = reshape(RXY(:,1), [100, 100]); YI = reshape(RXY(:,2), [100, 100]);
%! warped = imremap(I, XI, YI);
%! figure, imshow(warped);
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