Dylan M. TaylorandTed Mao 305bc3c971 Add craft-gainmap: ISO 21496-1, hdrgm and Apple gain maps, from LightCraft (#904) ...

* Add craft-gainmap: ISO 21496-1 and hdrgm gain map metadata, compute and apply, from LightCraft

Moved from lightcraft-codecs' gainmap.rs at 8ef35987 with its tests: the metadata reader and
writer and the arithmetic. The JPEG container (MPF index, two encoded images) stays in the app.

* craft-gainmap: Apple legacy gain-map reconstruction

Apple's legacy single-channel gain maps interpolate a linear gain ratio, not the log2 gain of
ISO 21496-1: apple::apply rebuilds the HDR rendition from a decoded base and the map, with the
headroom taken from the maker-note pair or the HDRGainMapHeadroom tag, checked inputs and
pixel-centre sampling.

Ported from storytold/lightcraft#3760 (which carries #1978).

---------

Co-authored-by: Ted Mao <tedmao@gmail.com>

2026-11-11 17:07:37 -05:00

..

apple.rs

Add craft-gainmap: ISO 21496-1, hdrgm and Apple gain maps, from LightCraft (#904)

2026-11-11 17:07:37 -05:00

lib.rs

Add craft-gainmap: ISO 21496-1, hdrgm and Apple gain maps, from LightCraft (#904)

2026-11-11 17:07:37 -05:00