[poppler] Implementing overprint in Splash

Albert Astals Cid aacid at kde.org
Mon Mar 21 12:47:43 PDT 2011

A Dilluns, 21 de març de 2011, Thomas Freitag va escriure:
> Hi all!
> 4. Support of overprint in pdftoppm
> To support overprint in pdftoppm we have to enable SPLASH_CMYK in
> pdftoppm and use it for rendering. But all output formats defined in
> pdftoppm uses RGB as output colorspace, and even the main output formats
> ppm and png do not support CMYK colorspace. Therefore we have to
> possibilities to support overprinting in pdftoppm:
> a) The easiest way would be to specify a new output format like i.e.
> jpegcmyk and create a jpeg image in CMYK colorspace where overprinting
> will be supported.
> b) The more interesting way is to add a new parameter -overprint, when
> set use splashCMYK8 as colorMode and when writing the output file
> convert it to RGB. The first implementation could use the poor
> colorspace conversion in Splash to convert the CMYK bitmap to RGB, but
> we should think of use little cms to do that work for us, which of
> course means that compiling pdftoppm will become more complex.
> Any suggestions from the community to point 4?

Both seem interesting :-)


> Thomas
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