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From: | Dave Arnold |
Subject: | Re: [ft-devel] GX support now working |
Date: | Mon, 22 Jun 2015 15:15:17 -0700 |
User-agent: | Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
Hi Werner, On 6/8/2015 2:20 AM, Werner LEMBERG wrote:
Adobe rasterizers typically use even-odd at small sizes and non-zero at larger sizes.Interesting. What's the rationale for that? And which ppem values are `small sizes'? I would also like to know whether this is a general thing, independent of the font format (i.e., TrueType vs. PostScript outlines).
I've checked around at Adobe, and find that my memory is incorrect. The small sizes are non-zero and the large sizes are even-odd. The threshold is 400 ppem. Below that size, a "center scan" algorithm is used. It is a newer algorithm than the original scan converter and produces better results. But it runs slower and takes more memory, so the original is still used at large sizes. The TrueType rasterizer that Adobe licenses from Microsoft has its own scan converter. Thanks. -Dave
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