[MPEG-OTSPEC] Removal of the CFF and CF2 from OFF standard (was: Proposal to make OFF complete)

Dan Rhatigan rhatigan at adobe.com
Thu Oct 8 01:33:39 CEST 2020

Adobe objects to the proposal to remove CFF and CFF2, as well. Every major implementer of OpenType supports CFF and CFF2, the former for sometimes decades, the latter for up to several years.

CFF is part of the PDF specification (ISO 32000-1) and CFF fonts are widely used, as well as bundled in places such as MacOS (the Hiragino family, for example). CFF2 is the forward-looking version of CFF, one that supports variability as well as non-variability.

CFF and CFF2 have important facilities not available elsewhere in OT, most importantly cubic Beziers and the PostScript approach to hinting. (Eric Muller & Terry Dowling have responded more on this email list on the rationale and merits of CFF hinting.)

CFF2, in addition, supports 32-bit glyph IDs, an important future-looking facility that is being discussed currently (https://github.com/MPEGGroup/OpenFontFormat/issues/10).

The compression benefits of CFF2 are substantial, and in large fonts such as the pan-CJK family we’re working on, the compression is quite significant.

We hadn’t responded earlier since this was first presented as a “suggestion”, and since extensive discussion around hinting has since happened. (Also, the rasterizer code is not proprietary; Adobe freely shared the code with FreeType and Microsoft, and Apple implemented their own.)

From: mpeg-otspec <mpeg-otspec-bounces at lists.aau.at> on behalf of Behdad Esfahbod <behdad at behdad.org>
Date: Wednesday, October 7, 2020 at 5:51 PM
To: "Levantovsky, Vladimir" <Vladimir.Levantovsky at monotype.com>
Cc: mpeg-otspec <mpeg-otspec at lists.aau.at>
Subject: Re: [MPEG-OTSPEC] Removal of the CFF and CF2 from OFF standard (was: Proposal to make OFF complete)

On Wed, Oct 7, 2020 at 3:35 PM Levantovsky, Vladimir <Vladimir.Levantovsky at monotype.com<mailto:Vladimir.Levantovsky at monotype.com>> wrote:
On Wednesday, August 19, 2020 12:40 AM Behdad Esfahbod wrote:
Moreover, I suggest CFF and CFF2 be removed from OFF. The claim-to-superiority of CFF format is: 1. better hinting, and 2. better compression. Re better-hinting, the interpretation of CFF hints is NOT specified anywhere. Adobe's code in FreeType is what we have. Re better compression, the existence of CFF in OpenType / OFF is partly why adding quadratic beziers to glyf table has continually not happened.

In reality, CFF only serves Adobe, who sells their rasterizer to MS / Apple platforms and serves only Adobe. Another example of Adobe abusing the "open" ideology / terminology is the Noto CJK / Adobe-equivalent. It's NOT open-source by any means. The sources are not available. That's something that I pointed out directly to Ken Lunde at one of his Unicode Conference presentations. Adobe is clearly aware of it. And I couldn't fix when I was at Google.

Rip the bandaid. Make open standards truly open.

With my SC29/WG3 member representative hat on (and _not_ serving in my capacity as a chair of this AHG) I object to this proposal. With many thousands of fonts currently deployed, and at least two (or more) different implementations available – this proposal, if considered, would do more harm than good.

Okay let me narrow down the proposal to removing CFF2 only.

Is there any evidence that there are "thousands of fonts currently deployed"? And is there any evidence of at least two different implementations (that is, that are not derived from same Adobe implementation)?


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