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Re: [csswg-drafts] "Can't be displayed" is undefined (#5046)

From: Mike Bremford via GitHub <sysbot+gh@w3.org>
Date: Wed, 06 May 2020 08:18:20 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-624507932-1588753099-sysbot+gh@w3.org>
Oh no. I've just realised my brain didn't fully engage with my final comment on #5045.

* `color(foo 0 0 1)` is in gamut because all the components are in the range 0..1
* `color(foo 0 0 2)` is out of gamut because one of the components is not in the range 0..1

For some reason I was imagining maths here, but of course testing whether a color is in the gamut of _it's own colorspace_ is just a trivial test to see if all components are in the range 0..1. Deciding whether a `color()` with a component value of "2" is invalid, or valid-but-out-of-gamut is largely academic, as it has the same result. Sorry, not sure how I missed that!

Chris, in #5045 you also mentioned that ensuring TAC (total area coverage) does not exceed the maximum for an additive colorspace would also be part of the in-gamut test. This might be more problematic - first because I don't believe the TAC limit is stored in the ICC profile, second because "registration black", where all the inks are at 100% (e.g. `color(fogra39 1 1 1 1)`) is sometimes used in print (for printer marks in the page margins). If the color() function consider this out-of-gamut and fell back to the alternative color, it would be a problem.

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Received on Wednesday, 6 May 2020 08:18:22 UTC

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