- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Sun, 24 May 2020 16:36:57 +0000
- To: public-css-archive@w3.org
> For your education : > Do you understand that Lab has a cubic root built-in ? @aurelienpierre I request you to read and understand [Positive Work Environment at W3C: Code of Ethics and Professional Conduct](https://w3c.github.io/PWETF/). Explanations are welcome, but there is no need to treat others contributing to this thread as if they are uneducated or incompetent. In addition, while I understand that posting a pirate PDF of a copyrighted book was probably well intentioned (and it is a good book, I have the first and second editions) please refrain from doing so in future. Moving on to your technical points: yes, Lab and LCH are intended to be perceptually uniform and they are being added to CSS for precisely that reason. Your claim that their sole reason for existing is to calculate deltaE is incorrect. They are used for many other purposes such as gamut mapping or the creation of perceptually even color scales or the creation of perceptually even color harmonies, to mention a few. And yes, compositing and blending should take place in a linear-light colorspace such as XYZ. The [Compositing and Blending](https://drafts.fxtf.org/compositing-1/) Level 1 specification does not, which I argued against for many years; eventually compatibility with industry standard tools (such as Photoshop blending modes) was deemed more important. So Compositing and Blending currently has the following known deficiencies: - it works directly on gamma-corrected RGB values rather than linear-light values - it uses the NTSC luma equation rather than the luminance of the sRGB values, to do greyscaling For backwards compatibility it will always do so by default, but I do hope to add linear-light alternatives as an opt-in alternative in the future. -- GitHub Notification of comment by svgeesus Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/4647#issuecomment-633257176 using your GitHub account
Received on Sunday, 24 May 2020 16:36:59 UTC