Colour came from whichever matrix rawler happened to key `D65`, the second
one was discarded, and the rendering was left linear. That is the dcraw
default, and FR-DEV-3e names it as the reason people abandon a converter in
the first hour: correct in the abstract, flat and poor on skin in practice.
The decoder now builds a camera profile.
- `ColorMatrix1/2` and `CalibrationIlluminant1/2`. rawler surfaces these as
an illuminant-keyed map — for DNGs from the tags, and for native formats
from its own camera database — so a Canon CR2 arrives with a tungsten
matrix and a daylight matrix exactly as an Adobe DNG of the same frame
would. Dual-illuminant support is therefore not a DNG feature here.
- `ForwardMatrix1/2`, read straight from the root IFD, because rawler parses
them and never surfaces them. Where a file carries both, they replace the
inverted colour matrix: the same relationship measured in the direction
rendering actually wants, rather than an inversion that amplifies the
measurement error exactly where skin lives.
- `AsShotNeutral`, used to estimate what the scene was lit by and to
interpolate between the two calibrations in mireds. The estimate is
circular — the temperature needs a matrix and the matrix needs the
temperature — so it is a fixed point, three rounds, as Adobe's SDK does it.
Bodies calibrated at neither D65 nor A stopped rendering uncalibrated as a
side effect: a Phase One IQ3 carries D55 and D75 and used to get no matrix
at all.
And a base curve, applied per channel in camera RGB between the last
adjustment and the conversion out of camera space — a toe, a steep midtone
and a shoulder, which is the difference between a photograph and a scan of
one. It is not an edit: no slider, nothing in the sidecar, because it
belongs to the body rather than to anything anyone decided, and a sidecar is
shared between bodies. It is not a develop node either, and `ops/README.md`
now records why. It evaluates on the tone curve's own spline rather than a
second copy, so a profile author placing a control point and a photographer
dragging one mean the same thing by it.
The curves are data. `core/dr-decode/profiles/base_curves.yaml` ships inside
the binary as a floor and is superseded by any copy on disk carrying a
higher `version:`, so a body can be added and distributed without a release
— and, under the GPL, contributed. The comparison runs both ways: a stale
pack cannot hold an upgraded binary back at last year's rendering.
Canon EOS 6D and R6, Nikon Z 6 and D750, Sony A7 III and Fujifilm X-T3 ship
with their own curves. Every other body gets a conservative default, which
is much closer to right than the identity is for any of them. A JPEG gets
none — it has already been rendered once, by the camera.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
dr-decode exposes four entry points rather than one decode, because
callers differ sharply in what they need (ARCH §3.2): culling wants a
preview, the grid wants metadata, only develop and export touch sensor
data. Fusing them forces a full decode where a header read suffices,
which is why Lightroom stalls ~2s per image while culling.
Smoke-tested against 1,852 real Canon CR2 files (EOS 6D, ~27MB each):
metadata 0.2ms from a 256KB header read, no full decode
preview ~250ms 5472x3648, downscaled to 2048 for display
jpeg 3.0ms
Two findings worth recording:
rawler 0.7.2's CR2 decoder implements only full_image; thumbnail_image
and preview_image are unimplemented trait defaults returning None. So
every rung of the preview ladder resolves to a full-resolution decode at
~250ms — 5x over NFR-P13's 50ms budget. CR2 does carry smaller IFDs, so
the fix is our own IFD walk or an upstream contribution. The ladder is
written now so that fixing it is a decoder change, not a change to every
caller. Recorded in milestone-v0.1 risks.
Preview.downscale_to bounds memory: a 5472x3648 RGBA preview is 79.8MB,
which exhausts a phone's budget after a handful of images. Box-filtered
so downscaled thumbnails do not alias.
Also fixed a RefCell double-borrow that panicked on first navigation —
`*x.borrow_mut() = *x.borrow() + 1` holds both borrows at once. Verified
with 10,000 programmatic navigations.
58 tests passing. Traceability 20.3% (29/143).
dtourolleandClaude Opus 5