- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Tue, 02 Mar 2021 16:22:02 +0000
- To: public-css-archive@w3.org
@Myndex wrote: > In Film/TV LUV or a variant is commonly used, at least "in the guts" of color grading gear. LAB is better suited to reflected colors. I have seen this "LUV for emissive color, LAB for reflective color" meme repeatedly, but never with any actual evidence. I believe it can be traced back to the 1976 CIE committee that standardized both LUV and LAB, and was given as a rather handwavy justification for standardizing both. Since then, ever paper or book or system that I have seen uses LAB and not LUV, unless: - it has moved on from colorimetry to color appearance modelling and thus uses CIECAM16 or whatever - it has moved on to HDR and thus (apart from Fairchild's HDR Lab) it uses IVCtCp, or Jzazbz - it is primarily concerned with modelling physical light transport, in which case it uses a linear-light model such as XYZ (or any linearized RGB space, provided it can handle out-of-range colors correctly) - it is illustrating gamuts in a vague and handwavy way, and thus is satisfied with a two-dimensional gamut representation, glossing over the fact that out of gamut colors can be inside the gamut triangle. It therefore uses the u'v' chromaticity diagram, which is not very perceptually uniform but is less broken than the xy one. More rigorous work is done with a 3D gamut volume, typically in Lab or in UCS-16 Jab. Checking just now the indexes for six books on various color science topics, LAB is mentioned all over and LUV gets a single mention near the beginning, mostly to note that it is not used, has poor distance metrics, and gives wildly inaccurate predictions for corresponding colors. If you have examples of CIE LUV being used, please cite them. If you have examples of a system derived from LUV being used, please name that system. -- GitHub Notification of comment by svgeesus Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5883#issuecomment-789029967 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Tuesday, 2 March 2021 16:22:03 UTC