--- a/main/image/NEWS	Thu Mar 15 02:49:14 2012 +0000
+++ b/main/image/NEWS	Thu Mar 15 12:43:09 2012 +0000
@@ -18,6 +18,7 @@
       iptchecknargin
       iptcheckstrs
       iptnum2ordinal
+      iscolormap
       normxcorr2
       wavelength2rgb
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main/image/inst/iscolormap.m	Thu Mar 15 12:43:09 2012 +0000
@@ -0,0 +1,39 @@
+## Copyright (C) 2012 Carnë Draug <carandraug+dev@gmail.com>
+##
+## 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} {} iscolormap (@var{cm})
+## Return true if @var{cm} is a colormap.
+##
+## A colormap is an @var{n} row by 3 column matrix.  The columns contain red,
+## green, and blue intensities respectively.  All entries should be between 0
+## and 1 inclusive.
+##
+## @seealso{colormap}
+## @end deftypefn
+
+function bool = iscolormap (cm)
+
+  if (nargin != 1)
+    print_usage;
+  endif
+
+  bool = false;
+  if (ismatrix (cm) && isnumeric (cm) && columns(cm) == 3 &&
+      min (cm(:)) >= 0 && max (cm(:)) <= 1)
+    bool = true;
+  endif
+
+endfunction