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I have a script that reduces sizes of CMYK PDFs. This script works in 9.26 very well, and now I have changed to 9.27 on the staging systems. I see the black color in some PDFs change to red. I just tried OpenSuSE 15.1 with GS 9.27, and an Ubuntu 18.04 with GS 9.26. I basically use this two step approach:

pdf2ps $cur_pdf ${cur_pdf%.*}.ps

and then 

ps2pdf -dPDFSETTINGS=/ebook -dColorImageDownsampleType=/Bicubic ${cur_pdf%.*}.ps /tmp/$cur_pdf

I discovered, that only specific "fully black" PDFs show this error, once I have other colors included, it seemingly works ok. So I tried to recreate a b/w picture in GIMP, saved to PNG, converted to CMYK tiff, then PDF, and conversion to /ebook works ok. But those PDFs attached in the link come from an agency using QuarkExpress or Indesign (which I don't have). Here is the link, with the originals and the (red) results with 9.27:

https://ln2.sync.com/dl/a23c0e570/znzscb5b-9ucpw8f6-97rgu5gq-cmumrnbk

I have tried to play with the ICC color settings:

-dPDFSETTINGS=/ebook 
-sColorConversionStrategy=RGB 
-sProcessColorModel=DeviceRGB 
-sDefaultRGBProfile=AppleRGB.icc 
-sOutputICCProfile=AppleRGB.icc 
-dNOQUIET

in GS, to no avail. An RGB for an eBook makes much more sense, as it is displayed on a screen, not on paper...

When I choose output device /screen I see the same behaviour, when I use prepress/pdfwrite or similar, it is ok, but then file size remains big.

pebwindkraft
  • 131

1 Answers1

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There seems to be an issue with GS in version 9.27. I have just downloaded the full version 9.50 (ghostscript-9.50-linux-x86_64.tgz) to the test system. I installed the binary into /usr/local/bin, which is searched in the $PATH before /usr/bin, where the old gs executable resides.

Now gs works (again) correctly. I continued to use the wrappers pdf2ps and ps2pdf in /usr/bin. I see some slight warnings on ".setpdfwrite" and "3000000 setvmthreshold". I hope that the issue was not linked to any of those :-)

Now black remains black, and is not converted to red anymore. Waiting for the 9.50 release now.

pebwindkraft
  • 131