The least-squares 3x3 that mapped the develop onto the camera's JPEG won
on luminance, whose variance is ~80x the chroma's, so it paid for its
match by crushing the R-G axis: 11.6 -> 4.6 standard deviations, against
8.3 in the camera's own preview and 12.3 in its JPEG. That is the olive
cast -- the sky and the rice both shifted yellow-green.
The colour chain was never at fault: camera_mul x rgb_cam already agrees
with LibRaw to the digit, and the app's fit is bit-identical to a numpy
reference of the same problem, which is how the 3x3 was cleared.
Fit only the per-channel tone curve now. R-G comes back to 8.6 (900px)
and 10.5 (full), and B/G lands on the preview's 0.841 to three places.
3dtours
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