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Coloring and blending to print PDF files in Ghostscript

I use Ghostscript to create tif gray sections for each Process and Spot color in the PDF. The process is as follows:

  • Ghostscript starts with tiffsep as a device
  • I am using ImageMagick with a grayscale file as a mask for painting on a white canvas using colors extracted from a PDF file.

But the colored selections are different from the colored ones in Adobe Print Preview.

I tried using ICC color profiles from Adobe (namely AdobeRGB1998 and USWebCoatedSWOP for CMYK) in both ImageMagick and Ghostscript, but the results are still disabled.

Ghostscript version: 9.14, IM: 6.8.9-5

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I really don’t understand your statement: "the colored splits are different from what is in the Adobe Print Preview." --- What do you compare with Adobe preview using?!? Did you know that Adobe Print Preview can use the default ICC built-in profile if and when the PDF itself does not contain it. This in itself can explain any difference you can "see" ...

In addition, in recent versions of ImageMagick, some important changes have occurred when it comes to color management: it has replaced the values -colorspace RGB (now it means non-linear color) and -colorspace sRGB (which now means linear color) - while until this change was the other way around . Read more about these changes here .

Have you consulted the official documentation on Ghostscript color management features? Its latest version is available here:

In any case, before you can achieve any significant and reliable colors for processing the results, you need to calibrate all your devices in the workflow (monitors, printers, scanners, cameras) - or at least check their calibration. Also note that these calibrations are only valid for environments with standard lighting (e.g. D50 or D65 ). It is important that your eyes truly recognize color differences or color matches.

Also, have you verified that your PDF does not use its own internal ICC built-in profile? In this case, you may need to add

 -dOverrideICC=true

force Ghostscript to apply the ICC profiles that you provide on the command line.

To force Ghostscript to use the ICC profiles that you provide, add these parameters to your commands:

 -sOutputICCProfile=/path/to/your/profile.icc

For the tiffsep output tiffsep you can also use the ICC N-Color (NCLR) profile and specify the color names in the profile, for example (for example)

 -sICCOutputColors="Cyan, Magenta, Yellow, Black, Orange, Violet"

When using device link profiles, you should use

 -sDeviceLinkProfile = /path/to/your/devicelinkprofile.icc

There is more LOT to learn about Ghostscript and color management ...

But since you did not give us any idea of ​​the exact commands that you used, nor a sample of your PDF files, nor an exact description of your problem, there are not many that can be advised with confidence.

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Source: https://habr.com/ru/post/972032/

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