Re: image downsampling quality
Krzysztof Kosiński <[email protected]>
| Newsgroups | gmane.comp.lib.cairo |
|---|---|
| Message-ID | <CAFLw2WRMP0WQrJYM20HumLXbm5Nn-moB7X7NBfeGj-v9O9dofw@mail.gmail.com> |
2014/1/2 Behdad Esfahbod <[email protected]>: > On 14-01-02 07:09 PM, Ray Gardener wrote: >> When using e.g. cairo_pattern_set_filter(pattern, CAIRO_FILTER_BEST) and >> the pattern uses a bitmap surface, is the filter only for upsampling? >> I have high-res bitmaps that, when drawn to occupy fewer canvas pixels >> (downsampled), >> they look like they're being nearest neighbour filtered. > > I think it's bilinear, which means if you are reducing to less than 50%, it > misses pixels. > > There's been tons of talk and patches to fix this in pixman over the years. > I'm not sure what the current status is. The current trunk is fixed, and uses Lanczos3 downsampling for CAIRO_FILTER_BEST. CAIRO_FILTER_GOOD uses box downsampling, which is roughly equivalent in quality to bilinear upsampling. Regards, Krzysztof -- cairo mailing list [email protected] http://lists.cairographics.org/mailman/listinfo/cairo