[Development] about the Cocoa/Freetype fontengine

[Konstantin Tokarev]

31.12.2017, 03:11, "Nikolaus Waxweiler" <madigens at gmail.com>:
>>>  We want to get to "Gamma 1.8, darkenend":
>>>  https://www.freetype.org/image/BlendingExamples.png
>>
>>  On Mac (FT and/or FT+FC *without* Infinality+Ultimate patches) I
>>  find 1.5 comes closer to the native CoreText font colour. 1.8 is too
>>  thin.
>
> 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!
>
>>  And for giggles, which one looks better and which more correct in
>>  this screenshot (of 2 Konsole windows under X11)?
>
> Both look off (right: hinting, left: autohinting), specifically the
> gamma correction. Looks more like a gamma of 1.0 plus maybe some
> thickening/smearing via the LCD filter. Is gamma correction enabled in
> your Qt build? No strong hinting preference here, still prefer left for
> the slightly cleaner look should you wonder.
>
> The ftview program from the freetype2-demos package will render stuff in
> the technical correct way I'm going on about with a default gamma of
> 1.8. Use the FREETYPE_PROPERTIES env thing to toggle darkening for CFF
> fonts. All of that is courtesy of Adobe.
>
>>>  Which confirms my claim that most users will give higher priority
>>>  to on-screen legibility than to design veracity. Very
>>>  understandably so.
>>
>>  Alternative explanation: people complain when something they know
>>  changes. Nobody could stand to use Macs if bitmap fonts were the
>>  pinnacle of on-screen legibility.
>
> Reworded: if most users have higher priority on on-screen legibility in
> the strongly hinted sense, nobody would have used Macs before Retina
> screens. Text on pre-Retina Macs is however quite readable if you get
> used to the look.

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

>
>>  Please re-read and ponder the difference between fixing something and
>>  "tweaking to reduce it".
>
> Reworded: you can't reduce the difference between different hinting
> strategies without rewriting the hinting. See the attached screenshot.
> Left is hinting, right is autohinting, both use the v40 hinting engine
> that discards changes to vertical stems. The designers chose to clamp
> horizontal stems to full pixels (the usual strategy in Win95 times),
> note the thickness jump between 18 and 19 and 30 and 31 pt. The
> autohinter instead pulls horizontal stems to the pixel boundary without
> changing the stem thickness/width, a different design/clarity trade-off.
> This is a fundamental difference you can't paper over. You can see this
> even on Windows when you look at Arial and some ttfautohinted font in a
> text waterfall.
>
> Well, okay, you could theoretically start to supersample on the y-axis
> and apply some black magic, but then you might as well use autohinting.
>
>>  Right, and where did *that* come from in discussion that's about font
>>  engine choice by the user?
>
> We are talking about giving devs the ability to ship Qt apps with
> switched font engines, no?
>
>>  That'd mean both...
>
> Yes :)
> ,
>
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-- 
Regards,
Konstantin