pdf with transparent image and cups raster filter

Paul Newall p.newalls at ntlworld.com
Thu Jun 10 10:36:47 PDT 2010


I have a cups raster filter, using colorspace CUPS_CSPACE_K or CUPS_CSPACE_CMYK
Some pdf files fail to print.  The common factor seems to be that they contain an image with some transparency.
The filter is behaving as though the raster was blank (every byte of the data = 0). It's possible that there's some problem with the filter, but before I spend a lot of time looking at that...
Are there any known problems with cups converting pdfs with transparency to raster format?
Any ideas for how I should investigate this?
Maybe the pdf files are not to specification in some way? Is there a pdf file validity check I can run? or are there sample "correct" pdf files somewhere I can download? Or sample postscript files with transparency that I can use to see if the problem applies only to pdfs?




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