Re: images

[Daniel J Sebald]

Daniel J Sebald wrote:
> John W. Eaton wrote:
>
> > On  8-Feb-2007, Daniel J Sebald wrote:
> >
> > | Ok, some more questions.  I see the issue with imshow(r,g,b).
> > | Legacy code converts those r,g,b components to a color map.  That's
> > | not required and probably not preferred.  Gnuplot can handle r,g,b
> > | components.
> > | | Should there be a general function, say __img__.m to handle all the
> > | cases of imshow, image, and imagesc?
> >
> > If there is duplication functionality, then yes it wouldn't hurt to
> > handle common cases in a single function.
>
>
> I've done this.  Since there is to be color components and a colormap, 
> they differ very little.  Limits are similar.  Seems worth doing right now.
>
> > | I guess a more basic question is should there be another "image"
> > | type, e.g., "rgbimage", or do both fall under the class "image"?
> > | I.e., another case?
> > | |     case "image"
> > |       if (have_img_data)
> > |         warning ("an axis can only display one image");
> > |       endif
> > |       have_img_data = true;
> > |       img_data = obj.cdata;
> >
> > As far as I know, there is only one "image" graphics object type in
> > Matlab, so for compatibility that's what we have.
>
>
> Yes, cdata can probably be three dimensional for the RGB components.  
> I've done that.
>
> > | Having multiple images shouldn't be too difficult.
> >
> > What is needed to do that?  Do you mean it would not be too hard to do
> > this in Octave now, or that it would not be hard to make gnuplot
> > handle multiple images on the same plot?
>
>
> Gnuplot can handle multiple images in the same command as far as I 
> know.  However, for now I'm leaving just one image per axis.  So, there 
> can be multiple images via subplot.  That seems useful enough to satisfy 
> most right now.  Multiple images on the same axis shouldn't be difficult.
>
> With that in mind.  For the time being I'm keeping the colormap as part 
> of the axis array.  Doesn't it seem logical that in one subplot we could 
> have one colormap and in another subplot a different colormap?  Well, 
> I've implemented this, but unfortunately there seems to be a bug in 
> gnuplot where the color map changes for both images.  I thought I'd 
> fixed that quite a while ago.  I'll investigate.

Oh, I recall the gnuplot issue there.  There can only be one palette for an X 
window.  gnuplot_x11 is set up so that each figure window is an X window.  I 
think we left off there wondering if each each subplot could be made its own X 
window.

So, there is a bug, but the bug is in gnuplot.  (Don't expect any imediate fix, 
it would be a project for this summer.)  However, the PostScript output should 
still work, so:

subplot(2,1,1)
image
colormap(ocean(64));
subplot(2,1,2)
image
print -depsc2 foo.eps

should give the correct EPS file.

The attached patch should be a step in the right direction.  The file diffs 
were created separately rather than recursively.  If I missed a file, let me 
know.

Dan

PS:  Should gray() be calling colormap()?  Or just creating the colormap that 
can be input to colormap(gray(64))?

--- image/__img__.m     1969-12-31 18:00:00.000000000 -0600
+++ /home/sebald/octave/__img__.m       2007-02-09 04:15:19.945242952 -0600
@@ -0,0 +1,73 @@
+## FIXME  HEADER INFO?
+##
+## Copyright (C) 1996, 1997 John W. Eaton
+##
+## This file is part of Octave.
+##
+## Octave 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, or (at your option)
+## any later version.
+##
+## Octave 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 Octave; see the file COPYING.  If not, write to the Free
+## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+## 02110-1301, USA.
+
+## -*- texinfo -*-
+## FIXME FIXED NUMBER OF INPUT PARAMETERS
+## @deftypefn {Function File} {} __img__ (@var{img})
+## @deftypefnx {Function File} {} __img__ (@var{x}, @var{y}, @var{img})
+## Generic image creation.
+##
+## The axis values corresponding to the matrix elements are specified in
+## @var{x} and @var{y}. If you're not using gnuplot 4.2 or later, these
+## variables are ignored.
+## @end deftypefn
+
+## Author: Tony Richardson <address@hidden>
+## Created: July 1994
+## Adapted-By: jwe
+
+function h = __img__ (x, y, img)
+
+  newplot ();
+
+  if (isempty (img))
+    error ("__img__: matrix is empty");
+  endif
+
+  if (isempty (x))
+    x = [1, columns(img)];
+  endif
+
+  if (isempty (y))
+    y = [1, rows(img)];
+  endif
+
+  xlim = [x(1), x(end)];
+  ylim = [y(1), y(end)];
+
+  ca = gca ();
+
+  s = __uiobject_image_ctor__ (ca);
+
+  s.cdata = img;
+  s.lims = [xlim ylim];
+
+  tmp = __uiobject_make_handle__ (s);
+
+  __uiobject_adopt__ (ca, tmp);
+
+  set (ca, "view", [0, 90], "xlim", xlim, "ylim", ylim);
+
+  if (nargout > 0)
+    h = tmp;
+  endif
+
+endfunction
--- image/colormap.m    2007-02-08 11:50:52.000000000 -0600
+++ /home/sebald/octave/colormap.m      2007-02-09 04:25:16.561543488 -0600
@@ -61,12 +61,12 @@
         error ("colormap: map must have values in [0,1]");
       endif
       ## Set the new color map
-      set (gcf (), "colormap", map);
+      set (gca (), "colormap", map);
     endif
 
   endif
 
   ## Return current color map.
-  cmap = get (gcf (), "colormap");
+  cmap = get (gca (), "colormap");
 
 endfunction
--- image/image.m       2007-02-08 11:50:52.000000000 -0600
+++ /home/sebald/octave/image.m 2007-02-09 04:14:16.427899056 -0600
@@ -56,33 +56,7 @@
     print_usage ();
   endif
 
-  if (isempty (img))
-    error ("image: matrix is empty");
-  endif
-
-  ## Use the newly added mode of "plot" called "with image".
-  if (isempty (x))
-    x = [1, columns(img)];
-  endif
-
-  if (isempty (y))
-    y = [1, rows(img)];
-  endif
-
-  ca = gca ();
-
-  s = __uiobject_image_ctor__ (ca);
-
-  s.cdata = img;
-
-  tmp = __uiobject_make_handle__ (s);
-
-  __uiobject_adopt__ (ca, tmp);
-
-  xlim = [x(1), x(end)];
-  ylim = [y(1), y(end)];
-
-  set (ca, "view", [0, 90], "xlim", xlim, "ylim", ylim);
+  tmp = __img__ (x, y, img);
 
   if (nargout > 0)
     h = tmp;
--- image/imshow.m      2007-02-08 11:50:52.000000000 -0600
+++ /home/sebald/octave/imshow.m        2007-02-09 04:07:11.000000000 -0600
@@ -146,21 +146,20 @@
     im(im > 1) = 1;
   endif
   
-  ## Convert to indexed image.
   dim = ndims (im);
   if (dim == 2)
     im = round ((size (color_map, 1) - 1) * im);
+    colormap (color_map);
+    image (im, initial_magnification/100);
+    colormap (old_colormap);
   elseif (dim == 3 && size (im, 3) == 3)
-    [im, color_map] = rgb2ind (im);
+    __img__ ([] , [], im);
+##FIXME NEEDED ANYMORE FOR A SPECIAL CASE?    ## Convert to indexed image.
+##    [im, color_map] = rgb2ind (im);
   else
     error ("imshow: input image must be a 2D or 3D matrix");
   endif
   
-  ## And now, we show the image.
-  colormap (color_map);
-  image (im, initial_magnification/100);
-  colormap (old_colormap);
-
 endfunction
 
 %!error imshow ()                           # no arguments
--- plot/__uiobject_image_ctor__.m      2007-02-08 11:50:56.000000000 -0600
+++ /home/sebald/octave/__uiobject_image_ctor__.m       2007-02-09 
04:13:32.576565472 -0600
@@ -32,6 +32,7 @@
     s.children = [];
 
     s.cdata = [];
+    s.lims = [];
 
     ## XXX FIXME XXX -- need to intialize all properties to default
     ## values here.
--- plot/__uiobject_draw_axes__.m       2007-02-08 11:50:56.000000000 -0600
+++ /home/sebald/octave/__uiobject_draw_axes__.m        2007-02-09 
03:52:21.000000000 -0600
@@ -222,7 +222,6 @@
     data = cell ();
 
     have_img_data = false;
-    img_data = [];
 
     xminp = yminp = zminp = Inf;
     xmax = ymax = zmax = -Inf;
@@ -239,7 +238,8 @@
          endif
          have_img_data = true;
          img_data = obj.cdata;
-
+         img_colormap = axis_obj.colormap;
+         img_lims = obj.lims;
 
        case "line"
          data_idx++;
@@ -537,28 +537,52 @@
       if (ischar (view_fcn) && strcmp (view_fcn, "gnuplot_internal"))
        have_data = true;
 
-       [y_dim, x_dim] = size (img_data);
+       [y_dim, x_dim] = size (img_data(:,:,1));
        if (x_dim > 1)
-         dx = abs (xlim(2)-xlim(1))/(x_dim-1);
+         dx = abs (img_lims(2)-img_lims(1))/(x_dim-1);
        else
          dx = 1;
        endif
        if (y_dim > 1)
-         dy = abs (ylim(2)-ylim(1))/(y_dim-1);
+         dy = abs (img_lims(4)-img_lims(3))/(y_dim-1);
        else
          dy = 1;
        endif
-       x_origin = min (xlim);
-       y_origin = min (ylim);
+       x_origin = min (img_lims(1:2));
+       y_origin = min (img_lims(3:4));
 
        ## Let the file be deleted when Octave exits or `purge_tmp_files'
        ## is called.
        [fid, fname] = mkstemp (strcat (P_tmpdir, "/gpimageXXXXXX"), 1);
-       fwrite (fid, img_data(:), "float");
+       if (ndims (img_data) == 3)
+         fwrite (fid, [img_data(:,:,1)(:) img_data(:,:,2)(:) 
img_data(:,:,3)(:)]'(:), "float");
+         format = "1:2:3";
+         imagetype = "rgbimage";
+       else
+         fwrite (fid, img_data(:), "float");
+         format = "1";
+         imagetype = "image";
+         palette_size = size(img_colormap,1);
+         fprintf (plot_stream, "set palette positive color model RGB maxcolors 
%i;\n", palette_size);
+         if (palette_size <= 128)
+           ## Break up command to avoid buffer overflow.
+           fprintf (plot_stream, "set palette file \"-\" using 1:2:3:4;\n");
+           for i = 1:palette_size
+             fprintf (plot_stream, "%g %g %g 
%g;\n",1e-3*round(1e3*[(i-1)/(palette_size-1) img_colormap(i,:)]));
+           end
+           fprintf (plot_stream, "e;\n");
+         else
+           # Let the file be deleted when Octave exits or `purge_tmp_files' is 
called.
+           [fid, binary_file_name, msg] = mkstemp([P_tmpdir,"/gpimageXXXXXX"], 
1);
+           fwrite(fid, img_colormap', "float32", 0, "ieee-le");
+           fclose(fid);
+           fprintf (plot_stream, "set palette file \"%s\" binary record=%d 
using 1:2:3;\n",binary_file_name,palette_size);
+         endif
+       endif
        fclose (fid);
 
-       fprintf (plot_stream, "plot \"%s\" binary array=%dx%d scan=yx flipy 
origin=(%g,%g) dx=%g dy=%g using 1 with image",
-                fname, x_dim, y_dim, x_origin, y_origin, dx, dy);
+       fprintf (plot_stream, "plot \"%s\" binary array=%dx%d scan=yx flipy 
origin=(%g,%g) dx=%g dy=%g using %s with %s",
+                fname, x_dim, y_dim, x_origin, y_origin, dx, dy, format, 
imagetype);
 
        plot_cmd = ",";
       else
--- plot/__uiobject_axes_ctor__.m       2007-02-08 11:50:56.000000000 -0600
+++ /home/sebald/octave/__uiobject_axes_ctor__.m        2007-02-09 
02:30:20.000000000 -0600
@@ -32,6 +32,7 @@
     s.parent = p;
     s.children = [];
     s.position = [];
+    s.colormap = __default_colormap__ ();
 
     h = __uiobject_make_handle__ (s);