new file mode 100644
--- /dev/null
+++ b/cmpermute.m
@@ -0,0 +1,94 @@
+## 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, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+## -*- 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(length(index),1);
+  for i=1:length(index)
+    rindex(index(i))=i;
+  endfor
+ 
+  ## readapt indices
+  Y=rindex(X);
+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, Y, newmap, Y2, newmap2
+%! X=rand(10,10);
+%! [X,map]=cmunique(X);
+%! [Y,newmap]=cmpermute(X,map);
+%! [Y2,newmap2]=cmpermute(X,map,rows(map):-1:1);
+
+%!# test we didn't lose colors
+%!assert(sort(map),sort(newmap)); 
+
+%!# test if images are equal
+%!assert(map(X),newmap(Y));
+
+%!# we expect a reversed colormap
+%!assert(newmap2(rows(newmap2):-1:1,:),map);
+
+%!# we expect reversed indices in image
+%!assert(X,max(Y2(:))+1-Y2);
+
+
+%
+% $Log$
+% Revision 1.1  2004/08/17 19:18:42  jmones
+% cmpermute added: Reorders colors in a colormap
+%
+%