Make a guess at the value before doing the binary search, cuts the number of conditionals by half. Not as much gain as I hoped but something.
Install ryg's float -> uint8 sRGB conversion code, which is much faster.
Some todo notes.
switch srgb convert to second ryg method, which is a bit faster (8% total speedup on upsampling test);
remove extra table in slowpath
optimization attempts, no meaningful changes
documentation, release data
Merge branch 'resample' of https://github.com/nothings/stb into resample