The Camera Raw default rested on comparing against Lightroom previews
of photographs that carry the user's Lightroom edits — HSL saturation
Blue +58, Aqua +50 and more, Highlights -40, Blacks -20, in every
DNG's XMP — so it measured the house look, not Camera Raw's base
rendering. Under the ACR3 curve _MG_9080 renders brighter than its
Lightroom preview (mean 0.39 against 0.31).
So the curve choice's first variant, the default, is the sigmoid again
and every raw renders as in 0.20.0 apart from baseline exposure. D21
and camera-profiles.md §12 now say the default is open, to be decided
by measuring against Lightroom exports of unedited photographs. Tests
that are about Camera Raw's tone choose it explicitly.
The rendering half of camera-profiles.md §11-§12 (D21). The view
transform gains a curve choice — Camera Raw (the default) or D19's
sigmoid. Camera Raw converts to linear ProPhoto, clips to [0, 1], runs
the curve on the largest and smallest channel and places the middle
one at its old fraction between them (RefBaselineRGBTone), and
converts back: hue kept, saturation raised where the curve is steep,
which is where Adobe Standard's look desaturated. White sets the input
scale (1 at its default, so sensor white is display white) and
contrast bends the input about grey (1 at its default).
The curve rides in the profile buffer after the tables: the profile's
own, else the ACR3 default, which the placeholder every profile-less
source binds also carries — so a CR2 with no .dcp still gets Camera
Raw's tone. Baseline exposure is a gain folded into the rendering
matrix at upload; RawImage::color_matrix stays the file's for the
merge's linear DNG.
camera_raw::apply_reference is the CPU statement; GPU tests hold the
shader to it on 256 colours and on greys against the ACR3 table. The
sigmoid's own tests now choose it explicitly.
The decoding half of camera-profiles.md §11-§12. RawImage gains
baseline_exposure: the file's BaselineExposure plus the chosen
profile's BaselineExposureOffset, as the DNG SDK sums them (+0.25 for
the library's 6D DNGs). A profile copied out of a DNG carries that
DNG's baseline as its offset, so the body's CR2s, which have none,
land at the same total.
ProfileTables gains the profile's ProfileToneCurve, resampled at
decode onto 1025 points with a natural cubic spline; an identity curve
counts as none. dr-types now holds Camera Raw's ACR3 default curve,
RawTherapee's adobe_camera_raw_default_curve copied value for value,
for every raw whose profile has no curve. Nothing renders through
either yet.
The first half of D20. dr-decode now finds a camera profile's HueSatMap
and LookTable in the order camera-profiles.md §4 gives: the profile a
DNG embeds, then a .dcp in the profiles directory whose
UniqueCameraModel names the body, then none. A .dcp brings its own
matrices, since its tables were measured against its forward matrix.
The HueSatMap is blended for the frame's colour temperature with the
same mired weight the matrices use, once per decode, and the result
rides on RawImage as profile_tables beside color_matrix, so every path
that renders a decoded file gets the same profile without a setter to
forget. Nothing applies the tables yet.
A profile whose embed policy allows copying can be written back out as
a .dcp (rawler's TIFF writer with the RC magic patched in), which is how
the library's 6D CR2s will get the Adobe Standard their DNGs carry. The
table type lives in dr-types because decode, pipeline and GPU all need
its layout. Tests read the library's 6D DNG when it is present.
The fused pass stops at "linear working values" when a sharpener, a
blur or a repair follows, and the detail passes convolve what it hands
on. Until now it handed on the rendering: the base curve, and since the
last commit the view transform, ran before the store. So every kernel
worked on display-referred values while its comments promised the
opposite — D19's second finding.
A fused pass composed for a detail stage now stops before the view
transform, and carries a second shader, `ComposedShader::view`, composed
from the same inputs. It runs the same prologue, for the positions a
fragment reads (a film's grain seeds from `source_px`) and the corners
it blacks out, takes its colour from the detail stage's result bound
where the sample cache would be, and runs the view transform, the
output transform and the mask reveal. `render_detailed` dispatches it
after the last detail pass, in the same encoder.
So no detail pass encodes any more. Every pass writes an intermediate,
the last one included, which retires three things that existed only to
make the last pass encode: `writes_output` and the runner's second
layout, the body-less resolve pass for an active kernel with nothing to
draw at this scale, and capture sharpening's pass-through, which now
emits no pass at all. An empty chain is a whole render: the view pass
reads the fused result directly. The detail stage no longer takes an
output space either, so `compose_detail_for` folds into
`compose_detail` and the space is named once, on the fused half.
The cost is one full-render read and write per frame when a detail
stage exists, and a third intermediate for a one-pass chain.
The base curve was a five-point spline on the unit square, flat past its
last point: every value above 1.0 left it as the same number, per
channel. Exposure and highlight recovery put values up there, and the
curve threw them away, then handed the result on as though it were
still scene-linear. The six per-body curves were also, by their own
file's account, hand-tuned shapes rather than measurements, and not
enough is known about where they came from to keep them (D19).
In their place, one view transform for every body (FR-DEV-3j): a
log-logistic sigmoid per channel, with the middle channel put back
between the other two so a hue survives the shoulder. Its two free
constants are solved from two conditions rather than set: scene grey
0.13, where the retired default curve put it, lands on display 0.18,
and the scene white four stops above grey lands on 1.0. So a highlight
a stop past sensor saturation still rolls into white, and the midtones
stay within 0.26 EV of the retired default between scene 0.03 and 1.0.
`dr_pipeline::view` holds the CPU reference and the WGSL, and the tests
there are FR-DEV-3j's acceptance criteria.
It is still fixed and still in the fused pass's tail, so a detail stage
still sees rendered values; the next commits make it an operation and
move it after the detail stage. It is skipped for a JPEG, as the base
curve was, and absent from the camera-space tap.
The base curve's database, its lookup and its twelve uniform slots go.
`RawImage` and `DemosaicedImage` lose the field, and the GPU test that
proved a curve reached the shader is replaced by one that renders the
view transform against the CPU reference and shows two highlights above
1.0 still render apart. The JPEG-and-sensor test now asserts the two
differ by exactly the view transform, where before an identity fixture
curve had made them match.
dtourolle