tree 7e657c3553e530ef7bb661f8d9b7c6477f7a0416
parent 8b35d611fbbbd124ec8cf93ca0f0e8a84c3ba689
author Paul Wilkins <paulwilkins@google.com> 1626098068 +0100
committer Paul Wilkins <paulwilkins@google.com> 1626275779 +0000

Optimize partition size selection near edges.

This patch forces split to smaller blocks where the current block
contains at least one sub block with very low variance and at least
one that has much higher variance.

The idea is that where a hard edge or feature exists next to a very
low variance region we want to use a smaller block size to improve
prediction and prevent propagation of ringing artifacts.

Only enabled with --allintra mode at present and only suitable for
all intra frames. For one problem image, psnr improved by 0.2db
(speed 6 & dq=3) and it also looked markedly better.

For more uniformly complex images the impact should be minimal.

Change-Id: I3cc8b2d994ce7a5b39d2c179974cf0c46296af51