--- a/scripts/ChangeLog	Thu Mar 11 20:06:36 2004 +0000
+++ b/scripts/ChangeLog	Fri Mar 12 18:16:23 2004 +0000
@@ -1,3 +1,8 @@
+2004-03-12  Stefan van der Walt  <stefan@sun.ac.za>
+
+	* image/imshow.m: Accept "truesize" argument.
+	Ignore current colormap.  New tests and demos.
+
 2004-03-10  Volker Kuhlmann  <VolkerKuhlmann@gmx.de>
 
 	* signal/sinewave.m: Allow N to default to M.

--- a/scripts/image/imshow.m	Thu Mar 11 20:06:36 2004 +0000
+++ b/scripts/image/imshow.m	Fri Mar 12 18:16:23 2004 +0000
@@ -18,42 +18,114 @@
 ## 02111-1307, USA.
 
 ## -*- texinfo -*-
-## @deftypefn {Function File} {} imshow (@var{x}, @var{map})
+## @deftypefn {Function File} {} imshow (@var{i})
+## @deftypefnx {Function File} {} imshow (@var{x}, @var{map})
 ## @deftypefnx {Function File} {} imshow (@var{x}, @var{n})
 ## @deftypefnx {Function File} {} imshow (@var{i}, @var{n})
 ## @deftypefnx {Function File} {} imshow (@var{r}, @var{g}, @var{b})
-## Display images.
+## Display an image.
 ##
-## @code{imshow (@var{x})} displays an indexed image using the current
-## colormap.
+## @code{imshow (@var{x})} displays an intensity image, estimating the 
+## number of gray levels.
 ##
 ## @code{imshow (@var{x}, @var{map})} displays an indexed image using the
 ## specified colormap.
 ##
-## @code{imshow (@var{i}, @var{n})} displays a gray scale intensity image.
+## @code{imshow (@var{i}, @var{N})} displays a gray scale intensity image of
+## N levels.
 ##
 ## @code{imshow (@var{r}, @var{g}, @var{b})} displays an RGB image.
+##
+## The string @code{truesize} can always be used as an optional
+## final argument to prevent automatic zooming of the image.
 ## @end deftypefn
+##
 ## @seealso{image, imagesc, colormap, gray2ind, and rgb2ind}
 
 ## Author: Tony Richardson <arichard@stark.cc.oh.us>
 ## Created: July 1994
 ## Adapted-By: jwe
 
-function imshow (a1, a2, a3)
+function imshow (varargin)
+
+  usage_str = "imshow (x) or imshow (x, map) or imshow (i, N) or imshow (r, g, b)";
 
-  if (nargin < 0 || nargin > 3)
-    usage ("imshow (args)");
-  elseif (nargin == 2)
-    if (length (a2) == 1)
-      [a1, a2] = gray2ind (a1, a2);
+  if (nargin == 0 || nargin > 4)
+    usage (usage_str);
+  endif
+  
+  ## Count nr of matrix arguments.
+  mvars = 0;
+  while (mvars < nargin && ismatrix (varargin{mvars+1}))
+    mvars++;
+  endwhile
+  
+  if (mvars < 1 || mvars > 3)
+    usage (usage_str);
+  endif
+  
+  ## All except imshow (r, g, b)
+
+  if (mvars != 3)
+    I = varargin{1};
+    if (max (varargin{1}(:)) <= 1)
+      # image in [0-1]; scale to [0-255]
+      I = I * 255;
+      M = gray (256);
     endif
-    colormap (a2);
-  elseif (nargin == 3)
-    [a1, a2] = rgb2ind (a1, a2, a3);
-    colormap (a2);
   endif
 
-  image (a1);
+  if (mvars == 1)
+    ## imshow (x)
+    ## Grayscale image [0-N] -- estimate gray levels.
+    N = 2^ceil (log2 (max(I(:))));
+    M = gray (N);
+  elseif (mvars == 2)
+    ## imshow (x, map) or imshow (x, N)
+    M = varargin{2};
+    if (isscalar (M))
+      M = gray (M);
+    endif
+  elseif (mvars == 3)
+    ## imshow (r, g, b)
+    r = varargin{1};
+    g = varargin{2};
+    b = varargin{3};
+    tmp = [r; g; b];
+    if (max (tmp(:)) > 1)
+      ## Normalise to [0-1].
+      r = r/255;
+      g = g/255;
+      b = b/255;
+    endif
+    [I, M] = rgb2ind (r, g, b);
+  endif
+  
+  ## Check for "truesize".
+  zoom = [];
+  for i = mvars+1:nargin
+    if (isstr (varargin{i}) && strcmp (varargin{i}, "truesize"))
+      zoom = 1;
+    endif
+  endfor
+
+  colormap (M);
+  image (I, zoom);
 
 endfunction
+
+%!error imshow ()                           # no arguments
+%!error imshow (1, 2, 3, 4, 5)              # too many arguments
+%!error imshow ([1,2], [2,3], [3,4], [4,5]) # too many matrix arguments
+%!error imshow ("image.png")                # filename not accepted as argument
+
+%!demo
+%!  imshow (loadimage ("default.img"));
+
+%!demo
+%!  I = loadimage ("default.img");
+%!  imshow (I, "truesize")
+
+%!demo
+%!  [I, M] = loadimage ("default.img");
+%!  imshow(I, M);