strange colormap behaviour with postscript printing

[Ben Abbott]

On Jan 18, 2009, at 5:58 AM, Petr Mikulik wrote:

>> So IMHO this really can be considered a gnuplot bug.
>
> It was designed this way when I have implemented pm3d; there were  
> only gray
> and rgbformulae palettes. The interpolated palette colours were  
> added later.
> So let us tell postscript to respect interpolated colour palette
> preferentially to the colour/gray setting. Then the fix is a one- 
> liner.
>
> In postscript file, change
> 	Color true and
> to
> 	Color InterpolatedColor or
>
> The patch for gnuplot source code is on sourceforge.
>
>> Another possibility that occurs to me is to convert the custom  
>> color map
>> to a monochrome version and have gnuplot respect that?
>
> With the above patch, any custom palette will keep the defined  
> colours and
> gnuplot will respect it.
>
>
> I think that Octave could pass the custom colormap() through a  
> "rgb2gray()"
> function before printing to any monochromatic device (not just  
> monochromatic
> postscript). Then the plots
> 	print('mono.ps', '-dps')
> 	print('color.ps', '-dpsc')
> will be same as in Matlab.
>
> ---
> PM

Petr,

I tried your patch

	http://sourceforge.net/tracker2/?func=detail&aid=2516634&group_id=2055&atid=102055

Unfortunately, 'mono.ps' and 'color.ps' inverted images (using the  
example below which accompanyied your patch).

	a=1./hilb(42);
	colormap(flipud(gray));
	imagesc(a); colorbar
	print('mono.ps', '-dps');
	print('color.ps', '-dpsc');

So it appears to me that the problem persists.

Ben