[OpenJDK 2D-Dev] Xrender bicubic interpolation

Clemens Eisserer linuxhippy at gmail.com
Thu Sep 13 18:58:34 UTC 2012


Unfourtunatly the situation is worse than I expected, currently
xrender doesn't seem to support anything better than billiniar
Because alias-names where used by the pipeline it didn't turn up
sooner (as they are guaranteed to be available, whereas the concrete
filter-implementation-name may change from platform to platform).

Seems at least for now we have to fallback for bicubic, I'll prepare a patch.

Thanks for bringing up this issue!

- Clemens

2012/9/3 Vadim Pakhnushev <vadim.pakhnushev at oracle.com>:
> Hi Clemens,
> We've found a bug in Xrender pipeline when setting interpolation rendering
> hint to bicubic by calling
> g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
> RenderingHints.VALUE_INTERPOLATION_BILINEAR) doesn't work as expected. In
> fact bicubic interpolation seems to fall back to bilinear, which can be
> clearly seen in the attached screenshot.
> I've attached the test, there are 3 images rendered with up scaling with
> various interpolation settings, upper 3 are rendered to the screen, lower 3
> to the BufferedImage which works as the reference. With
> -Dsun.java2d.Xrender=True the bicubic interpolated image is in fact
> interpolated using bilinear filter.
> Could you please take a look?
> Thanks,
> Vadim

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