Benchmark results comparing image from value variants

The benchmarks compare the current image from value against a new variant using the new xz folding of the blitter.

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Summary

• The current/old form is about 1.1 to 1.3 times slower than the new implementation, for a test image of 800x600x3 (0.5 MP). Extending the test image to 2 MP (1600x1200x3) shifts things up, if only a bit. Around 1.15. Going to 16 MP (4608x3456x3) it drops again to around 1.1.

• Good enough to switch as many blitters as we can to this mode. Definitely good enough in light of the fact that such xz loops have a good chance of being simd/vectorizable. See google's highway for a possibility.

• Details of the underlying differences

  • With the new xz axis of the blitter the image bands are folded into the columns, allowing a single loop to run over them all, instead of using many separate z-loops each going over the not many bands of a column.

Plots

For the 16 MP case.