image.m and gnuplot 4

[John W. Eaton]

On  8-Mar-2005, Fredrik Lingvall <address@hidden> wrote:

| I've have adapted image.m to use the pm3d map mode
| available in gnuplot 4. Now it should be possible to
| do for example:
| 
| image(x,y,A);
| 
| and get axis tics given by x and y.
| 
| The script tests if gnuplot 4 (or 3.8) is installed and if not
| it should fall back to the old methods (using xv or ImageMagick).

If gnuplot is used for plotting, it might be nice to use it for
displaying images as well.  The problem I see is that to do that, you
have to change a lot of gnuplot settings.  Will any of those changes
affect subsequent plots?  To avoid problems, I suppose we could have
Octave keep track of all plot related settings and then use reset
followed by setting the plot state prior to each plot.  But then any
gset commands issued by a user would be wiped out by a new plot
command.  I don't see a clean fix for this problem.

| Issues:
| 
| colormap do not seem to have any effect in the images.

Octave's colormap functions simply set or return a global variable,
__current_color_map__.  You need to use that.

jwe



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