Raphael Benedet wrote:
Hi,
When using the HW accelaration provided by DirectFB Unichrome gfx
driver, I get some visual artifacts when blitting 32-bits ARGB
surfaces.
For instance, if I blit a 800X600 ARGB surface loaded from a bitmap on
a black primary surface (800X600 too) with all alphas set to 255, I
get a diagonal line a little darker going from bottom-left to
top-right of the screen.
If I blit a surface with rendered white text on it on top of another
surface, I can see some lighter pixels in the no-text area appearing.
It seems these are rounding errors. It looks like some pixels are
blitted with an alpha value of 1-5 while the real value should be 0 or
that pixels with an alpha value of 255 are blitted with an alpha value
of 250-254. Not disturbing on the TV output, but on a good LCD, you
can clearly see them.
If I don't use the HW acceleration, the result is perfect of course.
I'm using DirectFB 0.9.24 with the viafb driver from "Patcher2K" on
top of a 2.6.10 kernel.
Am I the only one to get these artifacts?
No, it seems to be a rounding error in the hardware. Try a 32 bit
primary surface. It also only applies to blending!
--
Best regards,
Denis Oliver Kropp
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