The softISP AWB is pure gray world, so panning swings ColourGains with
the frame average (white wall renders green when the frame is
warm-dominated, dark desk renders red when cool-dominated) and the CCM,
interpolated over a CT estimated from those gains, amplifies and
quantizes the swings.
Patch 0015 (ours, original work) adds optional per-sensor Awb tuning to
the simple IPA: a piecewise-linear locus of calibrated illuminant white
points in gain space that the gray-world estimate is clamped to
(clampMargin), a per-stats-frame EMA on the applied gains (damping)
with a fast-converge path for persistent illuminant changes, and CT
interpolated from the applied gains' position along the locus - on the
same scale as the tuning file's ccms table - instead of the generic
estimateCCT(). Tuning files without whitePoints keep the previous
behaviour exactly, so every other sensor is unaffected.
imx896.yaml gains the locus from the stock tuning blob's 10-point
per-illuminant AWB calibration (white points and their exactly
reciprocal gain triplets, cross-validated): the 7 on-locus points as
nodes, the 3 fluorescent points admitted via clampMargin 0.35. The
5000 K label is the blob's own proven anchor; 2856 K (A) is locked by
the fluorescent trio projecting onto the 2856-5000 chord at ~3960 K
(TL84); the rest are geometry-derived approximations.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
