Re: [ft] FreeType rasterization grid fitting regime?

[David Turner]

Hello,

Sorry to say this, but it seems you don't understand what the code in 
ftraster.c does, or how it relates to the rest
of the font engine. Sadly, I won't be able to give you details here, 
since it'd be a bit long.

Have you tried running your program with the current FreeType CVS (which 
is about to be
released as 2.2.1 in a few days) ?. It contains a much better 
auto-hinter for CJK fonts, and this may improve
your rendering.

Hope this helps,

- David Turner
- The FreeType Project  (www.freetype.org)

Dakai Liu a écrit :
> Sorry If you have seen it on developer's mail list.
>
> Hello all,
>
> I am working on a rip project that uses FreeType 2.1.10 as font 
> engine. While I render an Asian font at 6 point size at 600x600 dpi, 
> the box size is 50x50. The font is a type1 font. FreeType produces 
> un-even horizontal strokes. During debug, I found that a macro in 
> ftraster.c:371
>
> #define SCALED(x)  ( ( (x) << ras.scale_shift ) - (ras.precision_half) )
>
> is trying to fit the points into the centre of a pixel. but some 
> certain Y value is already at the centre of a pixel. So SCALED moved 
> the Y value to the edge of the pixel. I guess this may contribute to 
> the un-evenness of a horizontal stroke. So I modified it to:
>
> #define SCALED(x)  ( (x) << ras.scale_shift )
>
> So the whole grid fitting changed, but the output looks much better. 
> also the serif at the top appeared. By examining the font file, at 6 
> point size at 600dpi, we should have 1 pixel sized serif.
>
> I am pretty much puzzled and need some enlightment. I enclosed the 
> font file.
>
>
> Thanks.
>
> ------------------------------------------------------------------------
>
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>   


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