--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -9,6 +9,6 @@
  The package also provides functions for feature extraction, image
  statistics, spatial and geometric transformations, morphological
  operations, linear filtering, and much more.
-Depends: octave (>= 3.8.0), signal (>= 1.2.0), general (>= 1.3.0)
+Depends: octave (>= 3.8.0), general (>= 1.3.0)
 License: GPLv3+, MIT, FreeBSD
 Url: http://octave.sf.net

--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,11 @@
  Summary of important user-visible changes for image 2.4.0 (yyyy/mm/dd):
 -------------------------------------------------------------------------
 
+ ** The implementation of normxcorr2 has been changed. The new method is
+    Matlab compatible and will return values in the range [-1 1].
+
+ ** The image package is no longer dependent on the signal package.
+
  ** The disk shaped filter of fspecial has been changed for Matlab
     compatibility. The elements on the border of the disk are now
     weighted by how much of them is covered by the disk. Note that

--- a/inst/normxcorr2.m
+++ b/inst/normxcorr2.m
@@ -1,4 +1,4 @@
-## Copyright (C) 2011 Carnë Draug <carandraug+dev@gmail.com>
+## Copyright (C) 2014 Benjamin Eltzner <b.eltzner@gmx.de>
 ##
 ## 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
@@ -14,27 +14,71 @@
 ## this program; if not, see <http://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
-## @deftypefn  {Function File} {} normxcorr2 (@var{template}, @var{img})
-## @deftypefnx {Function File} {} normxcorr2 (@var{template}, @var{img})
-## Compute the normalized 2D cross-correlation.
+## @deftypefn {Function File} {} normxcorr2 (@var{a}, @var{b})
+## Compute the 2D cross-correlation coefficient of matrices @var{a} and @var{b}.
 ##
-## Returns the normalized cross correlation matrix of @var{template} and
-## @var{img} so that a value of 1 corresponds to the positions of @var{img} that
-## match @var{template} perfectly.
 ##
-## @emph{Note}: this function exists only for @sc{matlab} compatibility and is
-## just a wrapper to the @code{coeff} option of @code{xcorr2} with the arguments
-## inverted.  See the @code{xcorr2} documentation for more details. Same results
-## can be obtained with @code{xcorr2 (img, template, "coeff")}
-##
-## @seealso{conv2, corr2, xcorr2}
+## @seealso{xcorr2, conv2, corr2, xcorr}
 ## @end deftypefn
 
-function cc = normxcorr2 (temp, img)
+function c = normxcorr2 (a, b)
   if (nargin != 2)
-    print_usage ();
-  elseif (rows (temp) > rows (img) || columns (temp) > columns (img))
-    error ("normxcorr2: template must be same size or smaller than image");
+    print_usage;
+  endif
+  if (ndims (a) != 2 || ndims (b) != 2)
+    error ("normxcorr2: input matrices must have only 2 dimensions");
+  endif
+
+  ## compute cross correlation coefficient
+  [ma,na] = size(a);
+  [mb,nb] = size(b);
+  if (ma > mb || na > nb)
+    warning ("Template is larger than image.\nArguments may be accidentally interchanged.");
   endif
-  cc = xcorr2 (img, temp, "coeff");
+
+  a = double (a);
+  b = double (b);
+  a = a .- mean2(a);
+  b = b .- mean2(b);
+  c = conv2 (b, conj (a (ma:-1:1, na:-1:1)));
+  b = conv2 (b.^2, ones (size (a))) .- conv2 (b, ones (size (a))).^2 ./ (ma*na);
+  a = sumsq (a(:));
+  c(:,:) = c(:,:) ./ sqrt (b(:,:) * a);
+  c(isnan(c)) = 0;
 endfunction
+
+%!test # basic usage
+%!shared a, b, c, row_shift, col_shift, a_dev1, b_dev1, a_dev2, b_dev2
+%! row_shift = 18;
+%! col_shift = 20;
+%! a = randi (255, 30, 30);
+%! b = a(row_shift-10:row_shift, col_shift-7:col_shift);
+%! c = normxcorr2 (b, a);
+%!assert (nthargout ([1 2], @find, c == max (c(:))), {row_shift, col_shift}); # should return exact coordinates
+%! m = rand (size (b)) > 0.5;
+%! b(m) = b(m) * 0.95;
+%! b(!m) = b(!m) * 1.05;
+%! c = normxcorr2 (b, a);
+%!assert (nthargout ([1 2], @find, c == max (c(:))), {row_shift, col_shift}); # even with some small noise, should return exact coordinates
+%!test # coeff of autocorrelation must be same as negative of correlation by additive inverse
+%! a = 10 * randn (100, 100);
+%! auto = normxcorr2 (a, a);
+%! add_in = normxcorr2 (a, -a);
+%! assert (auto, -add_in);
+%!test # normalized correlation should be independent of scaling and shifting up to rounding errors
+%! a = 10 * randn (50, 50);
+%! b = 10 * randn (100, 100);
+%! scale = 0;
+%! while (scale == 0)
+%! scale = 100 * rand();
+%! endwhile
+%! assert (max (max (normxcorr2 (scale*a,b) .- normxcorr2 (a,b))) < 1e-10);
+%! assert (max (max (normxcorr2 (a,scale*b) .- normxcorr2 (a,b))) < 1e-10);
+%! a_shift1 = a .+ scale * ones (size (a));
+%! b_shift1 = b .+ scale * ones (size (b));
+%! a_shift2 = a .- scale * ones (size (a));
+%! b_shift2 = b .- scale * ones (size (b));
+%! assert (max (max (normxcorr2 (a_shift1,b) .- normxcorr2 (a,b))) < 1e-10);
+%! assert (max (max (normxcorr2 (a,b_shift1) .- normxcorr2 (a,b))) < 1e-10);
+%! assert (max (max (normxcorr2 (a_shift2,b) .- normxcorr2 (a,b))) < 1e-10);
+%! assert (max (max (normxcorr2 (a,b_shift2) .- normxcorr2 (a,b))) < 1e-10);