commit 56ba91bbe4470411ea2c6c20dc8bc2f76f5f92db
author Urvang Joshi <urvang@google.com> Tue Jan 10 13:22:09 2017 -0800
committer Urvang Joshi <urvang@google.com> Thu Jan 26 18:03:33 2017 +0000
tree 013f6052770eeffcf728d7c0d3f78e8a71827d87
parent e1c0929f51542e6b018b703fcd0f9e8152660620

Palette: Don't store tokens for pixels outside image boundary.

If part of a block falls outside right and/or bottom image boundary,
then only store tokens for the part of it within the boundary.

Also, consider only the part of the block within the boundary when
calculating the number of colors in the image, deciding the base
colors for palette, RD calculation etc.

The part of color map corresponding to pixels outside the image
boundary is padded with color indices copied from same row/column.
This behavior is similar to how pixels outside the boundary are padded.

For screen_content set, this is improves compression performance by
0.038 overall. One clip, in particular, has a significant gain of 0.8.

Change-Id: I745ca032f313c5041aacc98c03ae4bfc33d840de