[MPEG-OTSPEC] COLR v1 updates for AMD 2

[Vladimir Levantovsky]

Thank you Peter for your hard work on this!

All, please review the issues raised on the MPEGGroup Github
<https://github.com/MPEGGroup/OpenFontFormat>  and provide your comments on
the proposed changes. 

 

For avoidance of any confusion, there are two different documents that are
both referred to using "WD" as a shorthand - one is the Working Draft output
document from the last MPEG Systems (SC29/WG3) meeting, and another one is a
working draft of the proposal (maintained in the Google Fonts repo) where
the revisions were made to address open issues discussed at the last
meeting, and new comments and issues raised as part of the public
discussion.

 

These proposed changes, along with the comments that will have been
submitted before the next WG meeting in late April, will be used as the
basis for preparation of the input contributions to the next WG meeting. Our
goal, reflected in the AHG mandate, is to finalize the draft standard to
make it ready for promotion to the Committee Draft stage.

 

Thank you,

Vladimir

 

 

From: mpeg-otspec [mailto:mpeg-otspec-bounces at lists.aau.at] On Behalf Of
Peter Constable
Sent: Monday, February 22, 2021 3:35 PM
To: MPEG OT Spec list (mpeg-otspec at lists.aau.at) <mpeg-otspec at lists.aau.at>
Subject: [MPEG-OTSPEC] COLR v1 updates for AMD 2

 

At the last SC29/WG3 meeting, a few open issues regarding COLR v1 were
discussed with consensus to have these addressed in the working draft. These
included some details regarding radial gradients in certain edge cases,
interpolation of colours in gradients, and handling of sRGB colours (linear
vs. non-linear scales) in blending. Since then, a few other issues were also
identified through review of the WD or in work on implementations.

 

With input from Google partners, Chris Lilley, Vlad, Just van Rossum, and
engineers at Microsoft, I've made revisions in the proposed WD in the Google
Fonts repo
<https://github.com/googlefonts/colr-gradients-spec/blob/master/OFF_AMD2_WD.
md>  for these various issues:

 

*	Issue #39: Add support for sweep gradients in COLR v1
<https://github.com/MPEGGroup/OpenFontFormat/issues/39> 
*	Issue #40: In COLRv1 current design for linear gradients doesn't
work well with transforms
<https://github.com/MPEGGroup/OpenFontFormat/issues/40> 
*	Issue #41: [AMD2 WD: COLR v1] Address
<https://github.com/MPEGGroup/OpenFontFormat/issues/41> "TBDs" in working
draft regarding open issues on radial gradients
*	Issue #42: [AMD2 WD: COLR v1] Address
<https://github.com/MPEGGroup/OpenFontFormat/issues/42> "TBD" in working
draft regarding interpolation of colours
*	Issue #43: [AMD2 WD: COLR v1] Add paint formats for more compact
representations in non-variable fonts
<https://github.com/MPEGGroup/OpenFontFormat/issues/43> 
*	Issue #44: [AMD2 WD: COLR v1] Add discussion of bounding box and
transformation in variable fonts
<https://github.com/MPEGGroup/OpenFontFormat/issues/44> 

 

Links to relevant pull requests in the Google Fonts repo are provided in the
comments for each issue.

 

Along the way, there were other smaller revisions made in the proposed WD.

 

 

 

Peter

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