[cairo] [PATCH] Revert "image: Use convolution filters for sample reconstruction when downscaling"

Krzysztof Kosiński tweenk.pl at gmail.com
Tue May 13 17:54:35 PDT 2014

2014-05-13 10:15 GMT+02:00 Uli Schlachter <psychon at znc.in>:
> This reverts commit fb57ea13e04d82866cbc8e86c83261148bb3e231.
> When running cairo-test-suite with the parameter "-a", it also runs each test
> with a non-zero device-offset and device-scaling. The above commit influenced
> the device-scaling results badly. E.g. some test results ended up with a black
> border at the top-most and left-most row that looked like there was an offset of
> "0.5" in drawing the image and thus pixels outside of the image were sampled.
> This can be seen by the influence that this revert has on the results from
> running CAIRO_TEST_TARGET=image ./cairo-test-suite -a:
> Before: 31 Passed, 489 Failed [1 crashed, 8 expected], 31 Skipped
> After: 225 Passed, 295 Failed [1 crashed, 8 expected], 31 Skipped
> Most of the failures that disappeared are from the device-scaling tests.
> With such disastrous results on the test suite, this cannot really be usable for
> real-world applications.

Without some way to use convolution-based downscaling, we cannot
release Inkscape 0.91, since working with large bitmaps (e.g. photos)
is impossible due to extremely poor output quality, and that is a core
use case. This is very bad news.

Regards, Krzysztof

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