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Seshat 1.7.3 keeps CMYK colours exactly as designed when it converts to CMYK

Seshat 1.7.3 converts only the RGB and spot colours of a print file; colours that are already CMYK, also through a profile, keep their exact values.

By Rekhu 12 November 2026 1 min read

Print professionals do not print RGB. But a file sent to print is often a mix: brand colours set in CMYK in the design program, and photos or screenshots in RGB. Only the RGB part should change.

What changed

CMYK stays exact. Design programs often write CMYK colours through a colour profile. A conversion to CMYK used to convert those again, so a brand colour of C72 M9 Y8 K13 could come out as C75 M21 Y13 K0. Now convert_cmyk and convert_profile keep every CMYK colour at its exact values, in shapes, text and CMYK photos.
RGB is converted as before. RGB photos and colours go to CMYK through their own embedded profile, within the ink limit.

Nothing changes in your code: the same fix gives a file whose CMYK plates match the design.

Seshat Developers

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