[MPEG-OTSPEC] Removal of the CFF and CF2 from OFF standard

Behdad Esfahbod behdad at behdad.org
Thu Oct 8 20:50:23 CEST 2020

On Thu, Oct 8, 2020 at 11:30 AM John Hudson <john at tiro.ca> wrote:

> On 08102020 9:48 am, Behdad Esfahbod wrote:
> Hence my call to make OFF *complete*, by either deprecating & removing
> parts that are not complete currently, or add as new work items to spec
> them.
> Same about script-shaping specifications. For that, I'm proposing new work
> items to develop script shaping specifications (Indic, Arabic, USE, etc)
> that are currently NOT part of OFF.
> Accepting that rasterisation and layout implementation specs should exist,
> whether they should exist as *part* of OFF is less obvious to me.

How so? OFF files include bytes (CFF/CFF2 hinting data as well as GSUB/GPOS
lookups) without specification of how to be used to display text using that
font. This is akin to an image format specification without a decoding
algorithm specified.

What is the use of such a file format standard then?

> The layout implementation spec is most critical, I think, because having
> different results in shaping and display—using the same input text and the
> same font—on different platforms is unacceptable to everyone. Having
> different rasterisation on different platforms is something we’re used to,
> and ‘acceptable to Adobe’ seems to me an peculiar criterion for determining
> which rasterisation needs to be specified. Does such a specification make
> other rasteriser implementations invalid? What if, for a specific platform
> or device, a non-conformant rasterisation is better? So perhaps what we
> need is an informational specification—*not a standard*—that enables
> reproducible implementation of what the code in FreeType does, while not
> favouring this over other implementations. And if not a standard, then ISO
> isn't the place for it.
> JH
> --
> John Hudson
> Tiro Typeworks Ltd    www.tiro.com
> Salish Sea, BC        tiro at tiro.com
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