Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/image-1.0.15/imresize.m b/octave_packages/image-1.0.15/imresize.m
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+## Copyright (C) 2005 Søren Hauberg
+## 
+## 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{B}= imresize (@var{A}, @var{m})
+## Scales the image @var{A} by a factor @var{m} using bicubic neighbour
+## interpolation. If @var{m} is less than 1 the image size will be reduced,
+## and if @var{m} is greater than 1 the image will be enlarged.
+##
+## @deftypefnx {Function File} @var{B}= imresize (@var{A}, @var{m}, @var{interp})
+## Same as above except @var{interp} interpolation is performed instead of
+## using nearest neighbour. @var{interp} can be any interpolation method supported by interp2.
+## By default, bicubic interpolation is used.
+##
+## @deftypefnx {Function File} @var{B}= imresize (@var{A}, [@var{mrow} @var{mcol}])
+## Scales the image @var{A} to be of size @var{mrow}x@var{mcol}.
+##
+## @deftypefnx {Function File} @var{B}= imresize (@var{A}, [@var{mrow} @var{mcol}], @var{interp})
+## Same as above except @var{interp} interpolation is performed. @var{interp} can
+## be any interpolation method supported by interp2.
+## @seealso{imremap, imrotate, interp2}
+## @end deftypefn
+
+function ret = imresize(im, m, interp = "bicubic")
+  if (nargin < 2)
+    error ("imresize: not enough input arguments");
+  endif
+  
+  [row, col, num_planes, tmp] = size (im);
+  if (tmp != 1 || (num_planes != 1 && num_planes != 3))
+    error ("imresize: the first argument has must be an image");
+  endif
+
+  ## Handle the argument that describes the size of the result
+  if (length (m) == 1)
+    new_row = round (row*m);
+    new_col = round (col*m);
+  elseif (length (m) == 2)
+    new_row = m (1);
+    new_col = m (2);
+    m = min (new_row/row, new_col/col);
+  else
+    error ("imresize: second argument mest be a scalar or a 2-vector");
+  end
+
+  ## Handle the method argument
+  if (!any (strcmpi (interp, {"nearest", "linear", "bilinear", "cubic", "bicubic", "pchip"})))
+    error ("imresize: unsupported interpolation method");
+  endif
+
+  
+  ## Perform the actual resizing
+  [XI, YI] = meshgrid (linspace (1,col, new_col), linspace (1, row, new_row) );
+  ret = imremap (im, XI, YI, interp);
+endfunction