Mailinglist Archive: radeonhd (365 mails)

[Matthias Hopf <mhopf@xxxxxxx>]

On Mar 03, 09 18:03:22 -0800, Yang Zhao wrote:
> The attached patch fixes the issue of blurry images under Xv, compared
> to unaccelerated rendering.
>
> The texture sampler for CbCr used to be configured to use bilinear
> interpolation when upscaling. This results in a smoothing of the
> chroma channels, and is perceived as being blurry when a lot of sharp
> changes in colour is present. Simply flip the bits to use
> nearest-point interpolation instead.

Yang, I wouldn't change that. AFAIU color subsampling in the normal
YCb'Cr' color spaces is defined to be interpolative. If it does look to
blurry, there could be a different bug. Also, with nearest-neighbor
interpolation at least I always stumble over hard edges at smooth
surfaces, especially if they are red.

BTW - I already tried to use bicubic filters once, and I couldn't get
them to work. Apparently they need a little extra love (read:
coefficients) to actually work.
Of course one can always emulate bicubic filters by manually fetching
the necessary samples.

Matthias

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