[gs-devel] Further development of 'tiffsep' device xefitra

Ray Johnston Ray.Johnston at Artifex.com
Thu Nov 29 09:48:46 PST 2007


The 'tiffsep' device supports > 8 components as long as it is
built with USE_COMPRESSED_ENCODING set to 1 which is set by default
in src/gdevdevn.h as long as COLOR_INDEX values are 64 bits (long long).
The value of GX_DEVICE_COLOR_MAX_COMPONENTS is 252 in the 8.61 release.

I don't see anything in the code that would limit the number of
separations to 8.

If you have a file with > 8 separations that is only generating 8
separations, please report a bug on bugs.ghostscript.com and attach
the file.

Ray Johnston

pp42 wrote:
> hello all,
> for my project I need a tool that renders all the separations of a PDF 
> file and creates single separation images of the CMYK and spot color 
> separations as well as a composite image that shows all of the 
> overprint areas 'properly'. Fortunately I found out that the 'tiffsep' 
> device in Ghostscript is fullfilling these requirements. Unfortunately 
> there's a restriction in the 'tiffsep' device, that it produces only 8 
> separations per pass, which still allows to get all of the separations 
> in additional runs of gs (which I tested successfully with version 
> 8.60) but it is not possible to obtain a composite image with all of 
> the separations of the PDF file, if the number of separations 
> (including CMYK) is higher than 8. In the gs documentation I found the 
> suggestion to build a composite image with e.g. a tool like 
> 'ImageMagick', which is not very helpful as long as I don't have a 
> description for combining the colors. From my understanding the 
> 'tiffsep' device uses the 'DeviceN' and 'Separation' functions from 
> the PDF file to create the composite image.
> Now, if I want to create a composite of more than 8 separation images 
> I would need to know how a spot color is mapped to the appropriate 
> CMYK values. For now I might get along with 8 separations, but as 
> there are printing presses available that can handle up to 12 colors 
> or more I probably will run into a problem here. So, are there any 
> plans to export such a description in upcoming versions of gs and are 
> there any plans to include some functionality to build a composite 
> image from single separations, as this would save me from putting them 
> together on my own or dealing with additional tools in my project.

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