Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / imtranslate.m

diff --git a/octave_packages/image-1.0.15/imtranslate.m b/octave_packages/image-1.0.15/imtranslate.m
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+## Copyright (C) 2002 Jeff Orchard
+##
+## 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 2
+## 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{Y}} = imtranslate (@var{M}, @var{x}, @var{y} [, @var{bbox}])
+## Translate a 2D image by (x,y) using Fourier interpolation.
+##
+## @var{M} is a matrix, and is translated to the right by @var{X} pixels
+## and translated up by @var{Y} pixels.
+##
+## @var{bbox} can be either 'crop' or 'wrap' (default).
+##
+## @end deftypefn
+
+## Author: Jeff Orchard <jjo@cs.sfu.ca>
+## bug fix: Eugeniy Mikhailov in 2009 (removing fftshift and ifftshift they do no good)
+
+function Y = imtranslate(X, a, b, bbox_in)
+
+       bbox = "wrap";
+       if ( nargin > 3 )
+               bbox = bbox_in;
+       endif
+
+       if ( strcmp(bbox, "crop")==1 )
+
+               xpad = [0,0];
+               if (a>0)
+                       xpad = [0,ceil(a)];
+               elseif (a<0)
+                       xpad = [-ceil(a),0];
+               endif
+
+               ypad = [0,0];
+               if (b>0)
+                       ypad = [ceil(b),0];
+               elseif (b<0)
+                       ypad = [0,-ceil(b)];
+               endif
+
+               X = impad(X, xpad, ypad, 'zeros');
+       endif
+
+
+       [dimy, dimx] = size(X);
+       x = fft2(X);
+       px = exp(-2*pi*i*a*(0:dimx-1)/dimx);
+       py = exp(-2*pi*i*b*(0:dimy-1)/dimy)';   % actually to correspond to index notation 'b' should be
+                                               % replaced with '-b'
+                                               % but I do not want to brake previous version compatibility
+                                               % note: it also must be done in the cropping iand padding code
+       P = py * px;
+       y = x .* P;
+       Y = real(ifft2(y));     % fft return complex number
+                               % for integer shifts imaginary part  is 0 
+                               % so real takes care of transfer from complex number to real
+
+       if ( strcmp(bbox, "crop")==1 )
+               Y = Y(  ypad(1)+1:dimy-ypad(2) , xpad(1)+1:dimx-xpad(2));
+       endif
+endfunction