On 4/10/19 1:04 AM, Bill Spitzak wrote: > How difficult is it to just make the gradients use dithering, so > they > produce 8-bit (or whatever) results directly but with the > dithering pattern in them? >
We don't have the destination bpp when we compute the gradients. Søren Sandmann explained the various issues with this approach earlier https://lists.freedesktop.org/archives/pixman/2018-April/004711.html Note that it is always possible to add fast paths for gradient+dithering if performance is an issue. > What other operations would need dithering (a large blur comes to > mind, > also zooming way in on an image in bilinear)? Any type of filter (eg blur) or zoom could benefit from dithering, as well as any high bpp to low bpp compositing (compositing to r5g6b5 was mentioned in one of the previous discussions). Although for that one proper gamma correction may be required. > I think the blue noise large pattern is a great idea. All credits go to Wikipedia :) By the way re-reading the email I linked reminded me -- Søren, I don't know if you are still reading this mailing list, but you said in that email one year ago: > I could elaborate on that subject and have done so several times in > the > past, but in my experience those long emails about pixman > internals were mostly just a waste of time. I don't recall a single > one of them ever resulting in a useful patch. Your emails (especially the two I linked above, but also a couple others) were instrumental in getting a good enough grasp on the pixman internals for writing the floating point gradient computation and dithering patches, so thank you for taking the time to share your knowledge and insights. Hopefully mine will be (are?) those long-awaited useful patches. - Basile _______________________________________________ Pixman mailing list Pixman@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/pixman