Block filling
Each plane has don’t care (X) and useful (U) pixels
For each 8x8 pixel block
- Mark pixels in block
- 64 X-pels ? Use DC of previous block
- 64 U-pels ? Leave it alone
- Mix of U- and X-pels ? Iterative smoothing algorithm
0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 1 0 0 0 0 1 1 1 1 0 0 0 1 1 1 1 1 0 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1
X X X X X X U U X X X X X U U U X X X X U U U U X X X U U U U U X X U U U U U U X U U U U U U U X U U U U U U U X U U U U U U U
U U U U U U X X U U U U U X X X U U U U X X X X U U U X X X X X U U X X X X X X U X X X X X X X U X X X X X X X U X X X X X X X