Re: [ft-devel] optimal configuration to render fonts using gamma correction

[Francesco Abbate]

Hi all,

I'm sorry I've disturbed this ML with my unclear questions. I did
found out by myself how to have optimal font rendering. What I was
missing was vertical font hinting because I was freely translating the
y coordinate by fractional amount so that vertical hinting was
actually lost. I understood now that vertical hinting is *very*
important to have good looking fonts.

Otherwise other important things I found out to have optimal rendering are:
- antialising (of course) with subpixel rendering (very important) =>
the gamma value is less important but it seems to me that a gamma of
1.5 is a very good comprimise. You can also completely drop gamma
correction and still it goods fine.
- you can turn FT_LOAD_FORCE_AUTOHINTING since freetype autohinting
seems to give excellent results
- optionally activate FT_LOAD_TARGET_LCD and FT_LOAD_TARGET_LIGHT but
without this latter the hinting is may be better (found out about them
looking in libXft source code)
- disable the font hinting along the horizontal axis (achieved by
doing a x100 scale transform along x before loading the glyph)
- use font kerning with fractional positioning along x and without
rounding of the coordinates

With all these attentions the results turns out to be excellent on the
par with the better font system I know of. I found also that the
results are better that Windows's ClearType (at least on XP), this
latter does have too much colored fringes for my taste.

Here a sample of the results that I obtain: http://imagebin.org/223827

I hope this can be helpful for other people since it took me a lot of
time to figure out all the details.

Best regards,
Francesco