Re: imagesc and no image...

[Al Niessner]

I attached a quit modification to image.m.  I have run it and know that
it works. It is easy to see how to add new viewing utilities, but the
image.m I have only called xv and xloadimage (2.0.16 for linux) so you
will need to add the ImageMagick back in. Also, you may want to handle
the error condition a little better than a printf. I am not an expert
with octave scripts.

Al

"John W. Eaton" wrote:
> 
> On 22-Jan-2001, Al Niessner <address@hidden> wrote:
> 
> | I installed xv and all works fine now. Octave needs an error message if
> | xv is not found. It was an easy fix though once I got running on another
> | machine and noticed that xv was being used to display the image.
> 
> Actually, Octave first tries display from ImageMagick, then xv, then
> xloadimage, so all three have to be missing before it will fail.
> 
> If you'd like to try your hand at implementing a better error message,
> please take a look at image.m, and submit a patch.
> 
> Thanks,
> 
> jwe

## Copyright (C) 1996 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, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.

## Display an octave image matrix.
##
## image (x) displays a matrix as a color image. The elements of x are
## indices into the current colormap and should have values between 1
## and the length of the colormap.
##
## image (x, zoom) changes the zoom factor.  The default value is 4.
##
## SEE ALSO: imshow, imagesc, colormap.

## Author: Tony Richardson <address@hidden>
## Created: July 1994
## Adapted-By: jwe

function image (x, zoom)

  if (nargin == 0)
    ## Load Bobbie Jo Richardson (Born 3/16/94)
    x = loadimage ("default.img");
    zoom = 2;
  elseif (nargin == 1)
    zoom = 4;
  elseif (nargin > 2)
    usage ("image (matrix, [zoom])");
  endif

  viewers = [ "xv" ; "xloadimage" ];
  foundViewer = 0;

  % See if we have a viewer to display the image with.
  rv = 0;
  for i=1:rows(viewers)
    rv = system (["which " viewers(i,:) " 2> /dev/null" ], rv);
    if (length(rv) > 1)
      foundViewer = i;
      break;
    endif;
  endfor;

  % if no viewer was found, throw an error and return
  if (foundViewer == 0)
    viewerList = "     ";
    for i=1:rows(viewers)
      viewerList = [ viewerList " " viewers(i,:) ];
    endfor;

    printf (["Could not find any of these viewers to display the image with:\n" 
viewerList "\n\n" ]);
    return;
  endif;

  ppm_name = tmpnam ();

  saveimage (ppm_name, x, "ppm");

  % now that we know which viewer to use, lets fill out the rest of the command
  if (foundViewer == 1)
    viewer = sprintf ([deblank( viewers(foundViewer,:)) " -expand %f %s"],
                      zoom, ppm_name);
  elseif (foundViewer == 2)
    viewer = sprintf ([deblank( viewers(foundViewer,:)) " -zoom %f %s"],
                      zoom*100, ppm_name);
  endif;

  rm = sprintf ("rm -f %s", ppm_name);

  ## Need to let the shell clean up the tmp file because we are putting
  ## the viewer in the background.

  command = sprintf ("( %s && %s ) > /dev/null 2>&1 &",
                     viewer, rm);

  system (command);

endfunction