Re: [ft-devel] Taming CFF_CONFIG_OPTION_DARKENING_PARAMETER_Y* for a gamma of ~2.2/sRGB?

[Nikolaus Waxweiler]

Hello Dave,
your response has motivated me to spend some time looking into linear 
blending :) It turns out that other people had the same idea before, I 
found https://bugs.freedesktop.org/show_bug.cgi?id=28549 but the 
discussion there seems to have died quickly and the bug reporter told me 
he lost interest and is waiting for high-DPI-screens. I too hope for 
200+dpi screens in the near future, but I want something to tide me over.

I looked through the demo pages he set up[1][2] and found a 
demonstration of concept in the form of a hack of pixman. I made the 
patch apply to the current version 0.32.6 and attached it here (I hope 
it's not too big for the list?). Build the patched pixman somewhere and 
test it from the build directory with 
"LD_PRELOAD=pixman/.libs/libpixman-1.so CAIRO_DEBUG=xrender-version=-1 
some-application-like-firefox". Chrome doesn't seem to work (different 
rendering library?), Firefox does.

First impressions: wow! Text renders much cleaner. Screenshots: 
http://imgur.com/a/Xb1at -- before/after with autohinted Liberation 
Sans, before/after with Adobe-CFF-engine-hinted Source Sans Pro. Use 
wheel thingy the corner of a preview to download full size image.

Best regards,
Nikolaus

[1]: https://bel.fi/alankila/lcd/
[2]: https://bel.fi/alankila/lcd/alpcor.html

pixman-0.32.6-glyphalphacorrection.patch.gz
Description: application/gzip