Re: [csswg-drafts] [css-color] Device cmyk still needed?

@danielhjames you seem to be saying something different from What @cabanier is.

Yes, authors want to input CMYK values directly, not input RGB that gets converted to CYMK. The questions is whether authors want/need to input CMYK values without specifying which CMYK that is. If you're specificying  US Web Coated SWOP CMYK colors, that's different from "deviceCMYK". That's using the US Web Coated SWOP color profile.

The same CYMK values on the same type of paper will come out different on different printing presses if you do not specify which profile is assumed/used.

For "deviceCMYK" values to come out right, you need to have not only optimized for the right type of paper & coating, but also for the specific model of printer and ink you're going to be using (and possibly how it's been calibrated). Not all printers and all inks have the same color as 100% cyan. The point of a profile is to say what you color you mean when you say 100% cyan. The point of not using a profile is to explicitly ask the printer not to worry about what color you mean,  and just use 100% of whatever exact color cyan is on this particular print press.

> Where the document is public, or printed on more than one continent, we have no way of knowing which profile to embed.

It's the other way around: when your document is public, or printed on more than one continent, if you do not specify a profile, the printer has no way of understanding which colors you mean.

When you specify a profile, you do not specify what the printer is going to be like, you specify what your colors mean. If that setting happens to match the profile to which the printer is set, thinks will work with minimal conversions, and all is great. If it does not match, your document gets adjusted automatically, and everything is still fine. If you do not embed a profile in you file, and instead rely on implicit knownlege of which profile the printer you plan to use will interpret it as, things only come out fine if the printer is indeed set up the way you expected. Print it anywhere else, and colors will be off.



I do believe that there is some limited need for `deviceCMYK`, but "I don't want to send RGB that gets converted", or "I've optimized for coated" isn't it.

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Received on Tuesday, 15 August 2017 13:34:58 UTC