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Re: [csswg-drafts] [css-color-4] Predefined CMYK colorspace (#3449)

From: Kari Pihkala via GitHub <sysbot+gh@w3.org>
Date: Thu, 15 Oct 2020 08:53:14 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-709003251-1602751992-sysbot+gh@w3.org>
[SVG Native](https://svgwg.org/specs/svg-native/) might support FOGRA39 in the future, but embedded SVG Native renderers may not want to use complex ICC color profiles for color conversion. A set of approximation functions or a simple look-up table might be preferred.

That is also the approach taken by Firefox and Chrome PDF viewers to convert CMYK to RGB. Many PDF documents use Adobe U.S. Web Coated (SWOP) v2 color profile for CMYK colors. But, web browser PDF viewers don't use Adobe's ICC profile to convert SWOP colors to sRGB.

Firefox pdf.js uses a set of math functions for conversion:
https://github.com/mozilla/pdf.js/blob/a373137304b548620da2b82c00a4edb3538bc711/src/core/colorspace.js#L823

Chrome's PDFium uses a look-up table:
https://pdfium.googlesource.com/pdfium/+/refs/heads/chromium/2021/core/src/fxcodec/codec/fx_codec_icc.cpp#1274

I don't know why they don't use the real ICC profile, but few advantages of these approaches is that they take less space and are faster than full ICC color profile conversion. Embedded SVG Native renderers may take the same approach for FOGRA39. Just something for you to consider while developing the smaller ICC profile..


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