DemosaicedImage::from_rgb_f32 takes the network's linear camera RGB and
stands it beside the classical source of the same photograph: the matrix,
profile tables and as-shot balance are that source's, the id is new, so
nothing downstream can tell which demosaic ran and every cache keyed on the
source sees a new one.
GrainBlend is the denoise's live control. It returns only the brightness of
the noise the network removed, taken after the as-shot balance and handed
back divided by it, so the grain is neutral in the finished picture; colour
speckle and demosaic false colour stay out. It writes a new source rather
than adding a term to the adjust shader: the blend depends on two images and
one number, a 20 MP pass is milliseconds, and a fresh source id is all the
adjust pass's caches need. The test reads it back: at 0 the network's
result, at 1 the same white-balanced step in every channel.
dtourolle
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