hqdn3d produces banding
|Reported by:||Björn Sonnenschein||Owned by:|
|Blocking:||Reproduced by developer:||no|
|Analyzed by developer:||no|
Summary of the bug: the temporal denoiser of the hqdn3d filter produces banding. This is mostly noticeable on fine gradients with low luma value and some noise. Seems that the filter tries to clamp a pixel's value over the time.
How to reproduce:
I have uploaded a short example raw file that will show banding in the thicker parts of the tree. There is not much noise, but this shows that some gradients get destroyed by the filter.
% ffmpeg -i input -vcodec dnxhd -acodec copy -vb 120000k -vf hqdn3d=0:0:8:8 output ffmpeg version N-37943-gc87c2d0 built on N-37943-gc87c2d0