Re: [ft-devel] ttfautohint: How to install

[vernon adams]

Hi Werner,

Do you think it's possible that the autohinter can be tweaked to lessen the 
effects of the aggressive vertical filtering of GDI?
or is it already at the limits of what's possible for GDI?

The feedback i'm getting from my screenshots is that the ttfautohint output is 
overall superior under DirectWrite to the original hinted fonts.  Just seems to 
be a little extra 'something' needed to get the GDI sorted too :)

many thanks

-vern






On 21 Jun 2011, at 14:33, Werner LEMBERG wrote:

>> 
>> there's still some 'curve flattening' at large sizes, but less
>> marked now.  I will post some full waterfall tests later today to
>> check all point sizes up to 48 ish.
> 
> The reason for the difference is an incredibly aggressive vertical
> filtering with GDI, I believe.  Have a look at the attached images to
> compare how ftview and Win98's GDI render glyph `o' from the
> ttfautohint version of the Ubuntu font:
> 
>  Ubuntu-R-TA-o-48px-1.0gamma-ftview.png
>  Ubuntu-R-TA-o-48px-Win98-GDI-Chrome12.png
> 
> GDI apparently paints horizontally isolated pale pixels as white, and
> blackens isolated dark pixels.  I consider this plain ugly.  At 48px,
> the glyphs in the top waterfall (Win98 GDI rendering) on the above web
> page look as if they had been rendered without anti-aliasing...
> 
> The FontForge snapshots demonstrate how the hinted outlines differ
> between the original hinting in Ubuntu (Ubuntu-R) and the ttfautohint
> version (Ubuntu-R-TA):
> 
>  Ubuntu-R-TA-o-48px.png
>  Ubuntu-R-o-48px.png 
> 
> As you can see, the ttfautohint intentionally aligns the hinted
> outline (green) at half-pixel borders, making it almost the same shape
> as the unhinted outline (black).  On the other hand, the original
> Ubuntu hinting is far more aggressive even at that large size,
> rounding to integer pixel values.