[MPEG-OTSPEC] WD for AMD 2 and COLR v1 enhancements

Tue Jan 5 21:34:11 CET 2021

Hello,

Is there an option to control color layers between glyphs. What I mean is
that the background color from one glyphs is not painting over the
foreground of the next (or previous) glyph.

In the attached image the shadow of the C is covering a bit of the R. And
it needs a absurdly wide spacing to make it work at all.

Best
Georg Seifert

On 4. Jan 2021, at 22:33, Vladimir Levantovsky <
vladimir.levantovsky at gmail.com> wrote:

Dear all,

Happy New Year! I hope you had a nice holiday break.

Please see attached for your review two input contributions I prepared
based on the input to this AHG (and public GitHub discussions) on behalf of
their respective authors. Since I did not receive any additional comments,
I intend to submit these contributions to WG document registry by end of
day today.

Please also note that the contribution m55831 [summarizing COLR v1 updates]
includes a number of highlighted unresolved topics that will need to be
discussed as part of the break-out group session during the week of the WG
meeting (Jan. 11-15, 2021). We need to finalize them by Jan. 15 if we plan
to recommend the promotion of the current Working Draft amendment to the
next Committee Draft stage.

Thank you all for your contributions,
Vladimir

From: Vladimir Levantovsky [mailto:vladimir.levantovsky at gmail.com]
Sent: Sunday, December 27, 2020 1:59 PM
To: Peter Constable <pgcon6 at msn.com>
Cc: MPEG OT Spec list (mpeg-otspec at lists.aau.at) <mpeg-otspec at lists.aau.at>
Subject: Re: [MPEG-OTSPEC] WD for AMD 2 and COLR v1 enhancements

Hello all,

Many thanks to Peter, Rod, Dominik, and many other people who have
contributed their review comments to the development and improvements of
the proposed text for COLR v1 amendment.

Since the deadlines for registration and upload of input contributions is
coming up soon, I would like to propose the following plan of actions:
- use the updated COLR v1 text from the public GitHub repo
https://github.com/googlefonts/colr-gradients-spec#annex-a-proposed-changes-to-isoiec-14496-22
as
the basis for the updated proposal;
- extend the current draft amendment with three additional amended parts
proposed as part of MPEGGroup/OpenFontFormat discussions (issues 36-38);
- submit the AHG Recommendation to consider the proposed changes be used as
a replacement to the current content of the Working Draft ISO/IEC
14496-22/AMD2.

Please submit your additional comments and proposed changes (if any) no
later than the end of day on December 30. In absence of additional
comments, and if no objections will have been raised by Dec. 30 - I will
consider the current text of the proposal, along with the additional
changes, to be approved by AHG consensus.

Thank you again for your contributions!
Vladimir

On Tue, Dec 22, 2020 at 10:00 PM Peter Constable <pgcon6 at msn.com> wrote:

In the past few weeks, I’ve been working with Rod Sheeter and Dominik
Röttsches at Google to draft updates for the working draft related to COLR
version 1. This fills out details for the new formats added in COLR version
1 as well as integrating with the existing text for COLR version 0 (which
doesn’t go away).

The proposed content for OFF Amendment 2 is available here:
https://github.com/googlefonts/colr-gradients-spec#annex-a-proposed-changes-to-isoiec-14496-22

When the COLR v1 enhancements were proposed here back in September, the
proposal doc had specific details on the structure formats, but not much
explanation of the semantics — how the formats represent different graphic
concepts and are to be processed. Much of the additional content in this
draft is conceptual explanation of the graphic operations that are
supported and how the structures are used to represent those, with several
figures to illustrate. The intent was not obvious before, but should be
clear now with these additions.

There have also been some further design enhancements in the proposed
draft: additional paint table formats for translate, rotate and skew
transformations—the separate formats are more compact than the matrix
format if only the specific transform is needed, and the rotate/skew
formats specify rotation angles in degrees, which is much better when
varying a rotation angle in a variable font than varying the matrix
elements.

There are a few open issues (“TBD: …” in that doc), but these are limited
in scope and shouldn’t hinder revision of the working draft considered by
SC29 at the January meeting.

AHG members are invited to review and comment. I’d suggest that general
comments not requiring specific action could be sent to this list, but for
suggested improvement, it would be better to track these in GitHub
issues—either in the GitHub repo above or in the MPEG/OFF repo:

Issues · MPEGGroup/OpenFontFormat (github.com)

Re COLR v1 and OpenType: I’ve been preparing a parallel draft for the next
OT version. That’s in MSFT’s typography repo, which is still a private
repo. The content will differ from the OFF content only in minor,
non-technical wording details.

Peter Constable
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<m55831-COLR_v1_updates-14496-22-AMD2.docx>
<m55833-proposed_additions-14496-22-AMD2.docx>
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