[Development] about the Cocoa/Freetype fontengine

[Nikolaus Waxweiler]

>> Fair enough, depends on your screen and how much you darken. Ideally,
>> you match the sRGB gamma curve of roughly 2.2 that in an ideal world,
>> your screen matches, too. Ha!
>
> I recall a difference in opinion between Apple and the rest of the world about
> what the correct gamma should be. To me 2.2 always looked too bleak.

I read somewhere that 2.2 best matched human perception *shrug*. Gamma
correction ideally corrects for your screen gamma curve, which ideally
matches the sRGB curve (roughly 2.2). Everyone who plays with
calibration knows that this is more wish than reality, so Adobe's
internal testing settled on 1.8 according to their Dave Arnold. If you
have an old Apple screen that uses 1.8 or something similar, you're
already on mark :)

> I calibrate my Mac screens btw, not using hardware but with the SuperCal
> utility.

I use DisplayCal :)

> All I can say is that I didn't turn it off and that the font smoothing gamma
> value matters.

Be more specific. Last I checked, default X11 builds use a gamma
correction of 1.0 unless you change the source (only exception, iirc:
CFF fonts since 5.9).

Also see https://bugreports.qt.io/browse/QTBUG-41590 -- I'd love to
close that one, I'd just need to make stem darkening work well for the
autohinter and possibly native TrueType hinting...

>> No strong hinting preference here, still prefer left for
>> the slightly cleaner look should you wonder.
>
> Hah. Both are Konsole under X11 with Novarese BQ Medium for menus and Ubuntu
> Mono for the terminal font. Left is with Infinality+Ultimate (preset #3), right
> is stock FT+FC.

Are you sure the preset isn't using the autohinter behind the scenes
for Ubuntu Mono? The increased x-height at the same point size
compared to native hinting is very characteristic :)

>> Reworded: you can't reduce the difference between different hinting
>> strategies without rewriting the hinting
>
> And what if you can switch the autohinter on or off per font (or per glyph if
> FontConfig allows that kind of control)? I see it's a FreeType property so
> technically this should be possible.

Yes you can, and it's my favorite mode of operation, but then you're
not using or rewriting the native hinting code but using something
else :)

> BTW, is there a technical reason to expect one cannot change a
> fontengine/fontdatabase anymore after the first fonts have been rendered?

What do you mean?

> Note that Mac OS X at least up to 10.5 allowed setting strong hinting in the system settings

Do you mean "font smoothing" (really more of a darkening strength
setting)? You can still set it from the command line: `defaults
-currentHost write -globalDomain AppleFontSmoothing -int [0123]`. I
set it to 1, still darker than I would like, but 0 turns it off and
makes fonts appear very gamma corrected ;)