BC7 DDS file entropy visualization

RDO GPU texture encoders increase the number/density of LZ matches in the encoded output texture. He's a file entropy visualization of kodim18.dds. The left image was non-RDO encoded, the right image was encoded with lambda=4.0 max backwards scan=2048 bytes.

Non-RDO:

RDO:

Non-RDO, one byte matches removed:

RDO, one byte matches removed:

fv docs:

"The output is fv.bmp with the given size in pixels, which visually
displays where matching substrings of various lengths and offsets are
found.  A pixel at x, y is (black, red, green, blue) if the last matching
substring of length (1, 2, 4, 8) at x occurred y bytes ago.  x and y
are scaled so that the image dimensions match the file length.
The y axis is scaled log base 10."

Tool source:

https://cs.fit.edu/~mmahoney/compression/fv.cpp