--- a/main/image/NEWS	Tue Nov 27 11:56:35 2012 +0000
+++ b/main/image/NEWS	Thu Nov 29 13:54:49 2012 +0000
@@ -1,6 +1,10 @@
 Summary of important user-visible changes for image 2.0.1:
 -------------------------------------------------------------------
 
+ ** The following functions are new:
+
+      checkerboard
+
  ** The plot produced by `imhist' is correctly scaled on the X axis so that the
     colorbar corresponds to the actual intensity of the stems; the given
     colormarp is used on the colorbar for indexed images; and the stems no

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main/image/inst/checkerboard.m	Thu Nov 29 13:54:49 2012 +0000
@@ -0,0 +1,66 @@
+## 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} {@var{board} =} checkerboard ()
+## @deftypefnx {Function File} {@var{board} =} checkerboard (@var{side})
+## @deftypefnx {Function File} {@var{board} =} checkerboard (@var{side}, @var{size})
+## @deftypefnx {Function File} {@var{board} =} checkerboard (@var{side}, @var{M}, @var{N})
+## Create checkerboard.
+##
+## Each tile of the checkerboard is made of four squares @var{side} pixels wide.
+## The created checkerboard itself will be @var{size}, or @var{M}x@var{N} tiles
+## wide.  Defaults to 4x4 tiles 10 pixels wide.
+##
+## @seealso{repmat}
+## @end deftypefn
+
+function [board] = checkerboard (side = 10, nRows = 4, nCols = nRows)
+  if (nargin > 3)
+    print_usage ();
+  endif
+  check_checkerboard (side,  "square side");
+  check_checkerboard (nRows, "number of rows");
+  check_checkerboard (nCols, "number of columns");
+
+  square = zeros (side * 2);
+  square(1:side, side+1:end) = 1;
+  square(side+1:end, 1:side) = 1;
+
+  greyvalue = 0.7; # matlab compatible
+
+  if (mod (nCols, 2))
+    ## odd number of columns, the central square needs to be split into 2
+    board = repmat (square, [nRows (nCols-1)/2]);
+    board = [board repmat(square(:,1:side), [nRows 1])];
+    square(logical (square)) = greyvalue;
+    board = [board repmat(square(:,side+1:end), [nRows 1])];
+    board = [board repmat(square, [nRows (nCols-1)/2])];
+  else
+    ## even number, it's simpler
+    board = repmat (square, [nRows nCols/2]);
+    square(logical (square)) = greyvalue;
+    board = [board repmat(square, [nRows nCols/2])];
+  endif
+
+endfunction
+
+function check_checkerboard (in, name)
+  ## isindex makes easy to check if it's a positive integer but also returns
+  ## true for a logical matrix. Hence the use for islogical
+  if (! isscalar (in) || ! isindex (in) || islogical (in))
+    error ("checkerboard: %s must be a positive integer.", name)
+  endif
+endfunction