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Re: [ft-devel] ttfautohint: How to install
From: |
vernon adams |
Subject: |
Re: [ft-devel] ttfautohint: How to install |
Date: |
Thu, 30 Jun 2011 08:22:05 +0100 |
Should also show that applying 'double links' rather than 'single links' to the
y-axis-stems of the 'O' is a better solution, but exactly same principle of
snapping to bottom pixel at alignment zone.
(above) original ttfautohint 'O'
(above) single links at y-axis stems)
(above) double links at y-axis stems
On 30 Jun 2011, at 08:09, vernon adams wrote:
> Sorry, i'm allways wary of posting images to a list.
>
> This should illustrate my observation;
>
> <PastedGraphic-2.tiff>
>
> (above) Upper case 'O', ttfautohint version, opened in Fontlab 'Truetype
> hinting' mode, showing alignment zones & pixels arranged by ttfautohints
> instructions. 27 ppem. Note the egging at top curve, as snapping is to pixel
> at TOP of alignment zone.
>
> (below) Same font & glyph but with a single link applied from at top edge
> (and one at baseline). note the top stem now snaps to pixel at bottom of
> alignment zone. All is now well with the glyph imo :)
>
> <PastedGraphic-3.tiff>
>
>
> hope that helps
> ps - this also reduces the 'vertical stretching' at certain ppems too!
>
> -vern
>
>
>
>
> On 30 Jun 2011, at 07:32, Werner LEMBERG wrote:
>
>>
>>>> If you limit hinting-range-max to a value where the blue zones are
>>>> still handled, the generated bytecode uses this hinting set for all
>>>> larger sizes also. Finding a good value for hinting-range-max has
>>>> to be done with trial and error, but a waterfall already indicates
>>>> bad sizes, so hinting-range-max must be less than that).
>>>
>>> hmm i have tested varying min-range & max-range - by shifting ranges
>>> i can get the 'egging issue' to move up/down a ppem size, so the
>>> issue persists but just at different ppem's.
>>
>> OK.
>>
>>> It seems to me that the egging issue is caused by the top curves of
>>> the 'o' snapping to the top edge of the pixel that corresponds to
>>> that alignment zone, if i force these curves to snap to the bottom
>>> edge of the alignment zone pixel then the egging is fixed! Of
>>> course then i need all pixels in the alignment zone to snap to the
>>> bottom of the pixel to get uniform x-height throughout all glyphs.
>>>
>>> Could there be a way to force pixel snapping to the bottom of pixel
>>> in some alignment zones like this with ttfautohint?
>>
>> While I basically understand what you write, I have some difficulties
>> to imagine it visually. Could you provide FontLab snapshots of an
>> `egged o', together with your proposed fix?
>>
>>
>> Werner
>
- Re: [ft-devel] ttfautohint: How to install, (continued)
Re: [ft-devel] ttfautohint: How to install, vernon adams, 2011/06/23
Re: [ft-devel] ttfautohint: How to install, vernon adams, 2011/06/29
Re: [ft-devel] ttfautohint: How to install, Werner LEMBERG, 2011/06/30
Re: [ft-devel] ttfautohint: How to install, vernon adams, 2011/06/30
Re: [ft-devel] ttfautohint: How to install,
vernon adams <=
Re: [ft-devel] ttfautohint: How to install, Werner LEMBERG, 2011/06/30
Re: [ft-devel] ttfautohint: How to install, vernon adams, 2011/06/30
Re: [ft-devel] ttfautohint: How to install, Werner LEMBERG, 2011/06/30
Re: [ft-devel] ttfautohint: How to install, vernon adams, 2011/06/30
Re: [ft-devel] ttfautohint: How to install, Werner LEMBERG, 2011/06/30