[MPEG-OTSPEC] proposal: COLR extension

[Peter Constable]

I've created an issue in the repo for discussion: Proposal: extension to COLR table (COLR v1)<https://github.com/MPEGGroup/OpenFontFormat/issues/20>.


Google has prepared a proposal<https://github.com/googlefonts/colr-gradients-spec/tree/rs> to extend the COLR table with significantly enhanced capabilities. This followed from initial discussion at a meeting in 2019 that included people from various companies, with a general consensus to proceed. I was commissioned by Google to adapt that into proposed revisions to the OpenType spec and to OFF.

Attached are preliminary drafts related to this:

  *   revisions to the COLR section-the bulk of the changes
  *   revisions to the Variations Common Table Formats section
  *   revisions to the CPAL section

Two variants for each are attached: one showing changes from OpenType 1.8.3, which would be approximately the same as changes from OFF:2019 + Amd1; and one showing the net result, with line numbering for easy reference.

Google and I are proposing that this be the basis for a proposed new edition of OFF.

Note: There is not a new edition in ISO's balloting process yet. That means that the technical content is not yet final, wrt ISO process. Assuming work on a new edition were approved at the next WG3 and SC29 meetings, technical balloting on the new edition would go well into 2021.

The draft for the proposed COLR table revisions is not yet complete, but there's enough in place that should allow a technical reader to get a pretty good understanding of proposed new structures and how they work. Also, the specifics on how the color gradation is calculated for a radial gradient have yet to be added, but the description of the structure used for it should, I think, give a clear idea of what the capabilities are. Some visual examples are forthcoming that will provide greater clarity.

The Google proposal was prepared by Behdad Esfahbod, Dominik Röttsches, and Rod Sheeter, with input and review feedback from several others including: Dave Crossland, Laurence Penney, Adam Twardoch, Cosimo Lupo, Rossen, Atanassov, Roel Nieskens, "Pomax", "bungeman", and myself. (Apologies if I missed anyone.)


Peter
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.aau.at/pipermail/mpeg-otspec/attachments/20200928/9b4a3233/attachment.html>