Add a useful package (from Source forge) for octave

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

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+## Copyright (C) 2004 Josep Mones i Teixidor
+##
+## 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}, @var{newmap}] = } cmpermute (@var{X},@var{map})
+## @deftypefnx {Function File} {[@var{Y}, @var{newmap}] = } cmpermute (@var{X},@var{map},@var{index})
+## Reorders colors in a colormap.
+##
+## @code{[Y,newmap]=cmpermute(X,map)} rearranges colormap @var{map}
+## randomly returning colormap @var{newmap} and generates indexed image
+## @var{Y} so that it mantains correspondence between indices and the
+## colormap from original indexed image @var{X} (both image and colormap
+## pairs produce the same result).
+##
+## @code{[Y,newmap]=cmpermute(X,map,index)} behaves as described above
+## but instead of sorting colors randomly, it uses @var{index} to define
+## the order of the colors in the new colormap.
+##
+## @strong{Note:} @code{index} shouldn't have repeated elements, this
+## function won't explicitly check this, but it will fail if it has.
+##
+## @end deftypefn
+
+
+## Author:  Josep Mones i Teixidor <jmones@puntbarra.com>
+
+function [Y, newmap] = cmpermute(X, map, index)
+  switch(nargin)
+    case(2)
+      index=randperm(rows(map));
+    case(3)
+      if(!isvector(index) || length(index)!=rows(map))
+       error("cmpermute: invalid parameter index.");
+      endif
+    otherwise
+      usage("[Y, newmap] = cmpermute(X, map [, index])");
+  endswitch
+
+  ## new colormap
+  newmap=map(index,:);
+
+  ## build reverse index
+  rindex = zeros(size(index));
+  rindex(index) = 1:length(index);
+ 
+  ## readapt indices
+  if(isa(X,"uint8"))
+    rindex=uint8(rindex-1);
+    ## 0-based indices
+    Y=rindex(double(X)+1);
+  else
+    Y=rindex(X);
+  endif
+endfunction
+
+
+%!demo
+%! [Y,newmap]=cmpermute([1:4],hot(4),4:-1:1)
+%! # colormap will be arranged in reverse order (so will image)
+
+%!shared X,map
+%! X=magic(16);
+%! [X,map]=cmunique(X);
+
+%!test # random permutation, 0-based index
+%! [Y,newmap]=cmpermute(X,map);
+%! # test we didn't lose colors
+%! assert(sort(map),sortrows(newmap)); 
+%! # test if images are equal
+%! assert(map(double(X)+1),newmap(double(Y)+1));
+
+%!test # reverse map, 0-based index
+%! [Y,newmap]=cmpermute(X,map,rows(map):-1:1);
+%! # we expect a reversed colormap
+%! assert(newmap(rows(newmap):-1:1,:),map);
+%! # we expect reversed indices in image
+%! assert(X,max(Y(:))-Y);
+
+%!shared X,map
+%! X=magic(20);
+%! [X,map]=cmunique(X);
+
+%!test # random permutation, 1-based index
+%! [Y,newmap]=cmpermute(X,map);
+%! # test we didn't lose colors
+%! assert(sort(map),sortrows(newmap)); 
+%! # test if images are equal
+%! assert(map(X),newmap(Y));
+
+%!test # reverse map, 1-based index
+%! [Y,newmap]=cmpermute(X,map,rows(map):-1:1);
+%! # we expect a reversed colormap
+%! assert(newmap(rows(newmap):-1:1,:),map);
+%! # we expect reversed indices in image
+%! assert(X,max(Y(:))+1-Y);
+
+%
+% $Log$
+% Revision 1.3  2007/03/23 16:14:36  adb014
+% Update the FSF address
+%
+% Revision 1.2  2007/01/04 23:44:22  hauberg
+% Minor changes in help text
+%
+% Revision 1.1  2006/08/20 12:59:32  hauberg
+% Changed the structure to match the package system
+%
+% Revision 1.4  2004/09/08 15:01:28  pkienzle
+% Redo tests: reduce # of shared variables; force full range of uint8
+%
+% Revision 1.3  2004/09/08 14:13:08  jmones
+% Synchronized with cmunique. uint8 support added. Tests working for 2.1.58
+%
+% Revision 1.2  2004/08/18 14:57:42  jmones
+% speed improvement suggested by Paul Kienzle
+%
+% Revision 1.1  2004/08/17 19:18:42  jmones
+% cmpermute added: Reorders colors in a colormap
+%
+%