An FFF (a 3FR converted on the desktop) has no colour matrix of its own:
the camera's stays in the original 3FR header the FFF carries as a
complete TIFF in private IFD0 tag 0xC51B. The new vendor::hasselblad
reader decodes 3FR / FFF through dng::decode_as and, when the file has
no matrix, takes the matrices from that header, so an FFF no longer
develops with the "camera RGB = sRGB" fallback (H4D-40 as-shot white
moves from xy 0.279, 0.356 to 0.325, 0.336).
RGGB checked against the camera preview on the CC0 H4D-40 FFF and CFV
3FR (raw.pixls.us 931 and 709). Synthetic tests cover the embedded
matrix, an own matrix winning, a missing or damaged header, and
truncated files.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J2NDVXA8jQQWeJb4YVTb6b
Claude
0f67225e83