[NTG-context] LMTX generates PDFs with non-working fonts on real printers

Leah Neukirchen leah at vuxu.org
Wed Oct 12 13:14:52 CEST 2022

Max Chernoff via ntg-context <ntg-context at ntg.nl> writes:

> Hi Leah,
>> > Leah and I are zooming in on the issue. It might relate to wrong font
>> > matrix default behavior in the pdf printer driver, and GS got a fix
>> > for that long ago, so maybe old printers with not-updated drivers can
>> > be affected.
>> >
>> > Once we're confident that we can catch it Leah (who does the low level
>> > introspective testing with viewers, printers and tools) likely will
>> > report on it and there will be a test file for users to test if what
>> > we do is okay before we apply the safeguard.
>> There's a write up now on the issue:
>> https://leahneukirchen.org/blog/archive/2022/10/50-blank-pages-or-black-box-debugging-of-pdf-rendering-in-printers.html
> Great write up! I was expecting the issue to be something quite simple,
> but it's actually fairly complicated. Especially considering that the
> issue only happens with a few printer models, I'm pretty impressed that
> you managed to find the problem. At least the fix appears quite easy.
> Seeing that you're modifying the font encoding, could you perhaps
> reconsider supporting hinting in LMTX? 
>    https://mailman.ntg.nl/pipermail/ntg-context/2022/106311.html
> Even with a high resolution screen, I can still see a difference, and
> the issue can show up in print too:
>    https://graphicdesign.stackexchange.com/q/5874
> I'm fairly confident that these issues are all hinting-related:
>    https://mailman.ntg.nl/pipermail/ntg-context/2022/106874.html
>    https://mailman.ntg.nl/pipermail/ntg-context/2022/105212.html
> Considering that all of the fonts included with ConTeXt are hinted, it
> seems like a shame to not include any of that data in the generated
> PDFs.

The last version of font-cff.lua should also copy the hinting-related
values of the CFF properly (/BlueScale, /StemSnap[HV] etc).
We fixed that on the side. ;)

Leah Neukirchen  <leah at vuxu.org>  https://leahneukirchen.org

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