[MPEG-OTSPEC] Draft AHG report for your review

Mon Jan 11 05:38:31 CET 2021

Thank you Peter,

Since the nature of this typographic/formatting change is purely editorial,
I don't think we need to bring this to the WG to discuss - I can easily
incorporate your proposed changes when editing the text of the updated
Working Draft of the amendment.

Thank you,

Vladimir

From: Peter Constable [mailto:pgcon6 at msn.com] 
Sent: Saturday, January 9, 2021 2:34 AM
To: Vladimir Levantovsky <vladimir.levantovsky at gmail.com>; 'MPEG OT Spec
list' <mpeg-otspec at lists.aau.at>
Subject: RE: [MPEG-OTSPEC] Draft AHG report for your review

Vlad:

Another late comment-something to consider in the WG discussion: While
re-reading the draft text for 5.7.11.1.6, there are references to "source
in" and "source out" compositing modes that aren't set apart
typographically, and that makes the wording a bit confusing. For example,
"The same effects can be implemented. by. selecting the source in composite
mode."

In the proposed WD content in the Google Fonts repo, I've made changes to
the typography so that the compositing mode names are always italicized and
follow the capitalization in the W3C doc; this makes the meaning in the text
clearer. The above example becomes, ". by. selecting the Source In composite
mode." You can see the specific changes in this commit:

https://github.com/googlefonts/colr-gradients-spec/commit/2938cb91372f4bfbd2
460139131f09bcf9687be3#diff-f8c59e8d70f0a695574ea35269cf5f70c46db8cc40daa2d5
e128e8c79be10528

Peter

From: mpeg-otspec <mpeg-otspec-bounces at lists.aau.at
<mailto:mpeg-otspec-bounces at lists.aau.at> > On Behalf Of Vladimir
Levantovsky
Sent: Friday, January 8, 2021 2:40 PM
To: 'MPEG OT Spec list' <mpeg-otspec at lists.aau.at
<mailto:mpeg-otspec at lists.aau.at> >
Subject: Re: [MPEG-OTSPEC] Draft AHG report for your review

Folks,

I have not received any responses / comments on the draft AHG report - it
will be presented as is.

Also, for the next week's breakout session on Font Format work - so far I've
got the following topics we need to cover to finalize the text of the
amendment:

-          In 5.7.11.1.2.1 Color Lines: when it comes to color
interpolation, currently the spec says that color values along the color
line are linearly interpolated - is this enough?

-          In 5.7.11.1.2.2 Linear Gradients: the description of the gradient
and rotation vectors, and effects the rotation vector has on the final
results are underspecified. Issues that need additional clarifications
include 
a) rotation effect on color interpolation results if the angular distance
between gradient orientation vector and rotation vector are more than 90
degrees in either direction (CW or CCW), and
b) what effect , if any, the magnitude of the rotation vector has.
(Currently, the spec is silent about it.)

-          In 5.7.11.1.2.3 Radial Gradients: what is the expected behavior
in case where both circles overlap with r > 0?

-          In 5.7.11.1.2.3 Radial Gradients: specify the expected behavior
in case where a transform flattens both circles and their centers to a line.

-          In 5.7.11.4 COLR table and OFF font variations - discuss and
incorporate the proposed changes in the last two paragraphs.

If anything is missing from this list, please let me know.

Thank you,

Vladimir

From: Vladimir Levantovsky [mailto:vladimir.levantovsky at gmail.com] 
Sent: Wednesday, January 6, 2021 7:47 PM
To: 'MPEG OT Spec list' <mpeg-otspec at lists.aau.at
<mailto:mpeg-otspec at lists.aau.at> >
Subject: Draft AHG report for your review
Importance: High

Dear all,

Please see attached the draft of the AHG report that I will present at the
upcoming MPEG Systems (SC29/WG3) meeting next week (Jan. 11 - 15). Your
comments are appreciated.

We do have a number of open issues that need to be resolved in order to
finalize COLR v1 specification - it would be best if these issues are
resolved by next week, and discussed as part of the Font Format break-out
group session during the WG meeting. Currently, this break-out session is
tentatively scheduled on January 13 at 21:00 UTC. We will be using one of
the available ISO Zoom rooms; however, the meeting access information will
only be available to WG members and cannot be shared publicly.

I would like to bring your attention to the specific part of the AHG
Recommendations section where a promotion of the current Working Draft to
the next PDAM stage is suggested (last paragraph, also highlighted). The
final outcome related to document promotion will likely be determined based
on the results of the WG discussions. Our possible options are to either
keep the document as the Working Draft and finalize all remaining issues
before the next  WG meeting in early April, or to recommend promoting the
document to the next PDAM stage, and address the remaining _minor_ issues as
part of the ballot comments. I'd like to remind you that in order to be able
to process the ballot in time for the next meeting, it will likely be
published as two-months ballot, and the time period for submission of
comments will be very short (most National Bodies require comments to be
submitted at least three weeks prior to ballot closing date).

Please respond to this email with any proposed changes and corrections to
the AHG report by the end of day Friday, Jan. 8th - No comments will be
interpreted as approval!

Thank you,

Vladimir

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