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Replace the per-body base curve with a scene-referred view transform

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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.
This commit is contained in:
dtourolle
2026-09-27 16:52:53 -04:00
parent db7b84795c
commit 37a6d99dc4
23 changed files with 564 additions and 1442 deletions
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core/dr-gpu/src/adjust.rs
+21 -41
View File
@@ -34,16 +34,6 @@ use crate::{DemosaicedImage, GpuContext, GpuError};
/// reads them.
const RESERVED_FIELDS: usize = dr_pipeline::RESERVED_UNIFORM_FIELDS;
/// TRACES: FR-DEV-3e
/// The two crates must agree on how many points a base curve has.
///
/// `dr-decode` reads them from the profile database and `dr-pipeline` declares
/// the uniform slots; this file is the only place the two meet, and it packs
/// them by index. A disagreement would not fail to compile — it would upload a
/// curve with a point missing or a stale float in it, which renders as a
/// plausible-looking wrong tone response. Cheaper to catch here, at build time.
const _: () = assert!(dr_decode::base_curve::POINTS == dr_pipeline::BASE_CURVE_POINTS);
/// Runs composed operation chains against demosaiced images.
pub struct AdjustPass {
ctx: GpuContext,
@@ -1275,22 +1265,6 @@ impl AdjustPass {
// runs. See `DemosaicedImage::is_non_linear`.
let non_linear = if source.is_non_linear() { 1.0 } else { 0.0 };
uniforms[12..16].copy_from_slice(&[wb[0], wb[1], wb[2], non_linear]);
// TRACES: FR-DEV-3e
// The camera profile's base curve, packed the way the generated block
// declares it: four x, four y, then the fifth point and the flag. The
// flag is what lets one compiled shader serve a profiled body and an
// unprofiled one, so the pipeline cache is not split in two by which
// camera took the frame.
//
// Written here rather than at the call site so that *both* callers —
// the plain render and the masked one — carry the profile. Filling it
// at one of them was how the two halves of this merge each had it.
let curve = source.base_curve();
let on = if curve.is_identity() { 0.0 } else { 1.0 };
let b = dr_pipeline::BASE_CURVE_UNIFORM_OFFSET;
uniforms[b..b + 4].copy_from_slice(&curve.xs[0..4]);
uniforms[b + 4..b + 8].copy_from_slice(&curve.ys[0..4]);
uniforms[b + 8..b + 12].copy_from_slice(&[curve.xs[4], curve.ys[4], on, 0.0]);
uniforms
}
@@ -1478,8 +1452,6 @@ impl AdjustPass {
uniforms[4..8].copy_from_slice(&[0.0, 1.0, 0.0, 0.0]);
uniforms[8..12].copy_from_slice(&[0.0, 0.0, 1.0, 0.0]);
uniforms[12..16].copy_from_slice(&[1.0, 1.0, 1.0, non_linear]);
let b = dr_pipeline::BASE_CURVE_UNIFORM_OFFSET;
uniforms[b + 10] = 0.0;
let params_buf = self
.ctx
@@ -1707,7 +1679,7 @@ pub(crate) fn numbered(src: &str) -> String {
#[cfg(test)]
mod tests {
use super::*;
use dr_decode::{BaseCurve, CfaPattern, CropRect, RawImage};
use dr_decode::{CfaPattern, CropRect, RawImage};
use dr_pipeline::ops::{colour_mixer, exposure, saturation};
use dr_pipeline::EditGraph;
// For `Operation::detail`, which is how `the_whole_chain_at_once_compiles`
@@ -1745,7 +1717,6 @@ mod tests {
// Identity, so the test reasons about the operations alone
// rather than about a camera's colour response.
color_matrix: Some([1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0]),
base_curve: BaseCurve::IDENTITY,
samples_per_pixel: 1,
profile: None,
make: String::new(),
@@ -1949,7 +1920,6 @@ mod tests {
white_level: 16383,
wb_coeffs: [1.0, 1.0, 1.0, 1.0],
color_matrix: Some([1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0]),
base_curve: BaseCurve::IDENTITY,
samples_per_pixel: 1,
profile: None,
make: String::new(),
@@ -2538,7 +2508,6 @@ mod tests {
white_level: 16383,
wb_coeffs: [1.0, 1.0, 1.0, 1.0],
color_matrix: Some([1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0]),
base_curve: BaseCurve::IDENTITY,
samples_per_pixel: 1,
profile: None,
make: String::new(),
@@ -2642,7 +2611,6 @@ mod tests {
white_level: 16383,
wb_coeffs: [1.0, 1.0, 1.0, 1.0],
color_matrix: Some([1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0]),
base_curve: BaseCurve::IDENTITY,
samples_per_pixel: 1,
profile: None,
make: String::new(),
@@ -3227,11 +3195,16 @@ mod tests {
}
#[test]
fn a_jpeg_and_sensor_data_agree_on_the_same_scene_value() {
// The two producers must be interchangeable. A mid-grey that is
// linearly 0.216 (sRGB 128) arriving as sensor data and as a JPEG
// must render the same, or an edit would mean different things
// depending on which decoder opened the file.
fn a_jpeg_and_sensor_data_differ_by_exactly_the_view_transform() {
// TRACES: FR-DEV-3j
// The two producers must be interchangeable up to the rendering. A
// mid-grey that is linearly 0.216 (sRGB 128) arriving as sensor data
// is scene-referred and goes through the view transform; arriving as
// a JPEG it is already a rendering and must come out as it went in.
// Before D19 the fixture's identity base curve made both unrendered
// and this asserted they matched; what it guards is unchanged — the
// linearisation of each agrees — but the rendering between them is
// now always there for sensor data.
let Some(ctx) = ctx() else { return };
let mut pass = AdjustPass::new(&ctx);
let shader = EditGraph::default_chain().compose();
@@ -3250,11 +3223,18 @@ mod tests {
read_centre(&ctx, t)
};
let delta = (i32::from(from_sensor[0]) - i32::from(from_jpeg[0])).abs();
let scene = 3537.0 / 16383.0;
let viewed = dr_pipeline::view::Sigmoid::default_curve().channel(scene);
let expected = (dr_types::Transfer::Srgb.encode(viewed) * 255.0).round() as i32;
let delta = (i32::from(from_sensor[0]) - expected).abs();
assert!(
delta <= 3,
"the same scene value rendered {from_sensor:?} from sensor data \
and {from_jpeg:?} from a JPEG"
"sensor data rendered {from_sensor:?}, expected about {expected}"
);
let delta = (i32::from(from_jpeg[0]) - 128).abs();
assert!(
delta <= 3,
"a JPEG was rendered again: {from_jpeg:?} from sRGB 128"
);
}
}