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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/tests/base_curve.rs
-181
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@@ -1,181 +0,0 @@
//! TRACES: FR-DEV-3e
//! The camera profile's base curve, end to end on a device.
//!
//! The unit tests either side of this one check halves. `dr-decode` asserts
//! that the shipped database parses and that every curve in it lifts its
//! midtones; `dr-pipeline` asserts that the generated WGSL evaluates a curve
//! in the right place. Neither would notice if the two agreed with each other
//! and both were wrong — a curve packed into the wrong uniform slots, or a
//! flag read from the wrong component, satisfies both and renders nothing.
//!
//! So this renders real pixels twice, once with a profiled body's curve and
//! once with the identity, and asserts the difference is the one a base curve
//! is for: midtones lifted, black still black, white still white.
use dr_decode::{BaseCurve, CfaPattern, CropRect, RawImage};
use dr_gpu::{AdjustPass, Demosaicer, GpuContext};
use dr_pipeline::EditGraph;
const SIZE: u32 = 16;
fn ctx() -> Option<GpuContext> {
pollster::block_on(GpuContext::new_headless()).ok()
}
/// A flat RGGB frame at `level` out of 65535, carrying `curve`.
///
/// Every photosite the same value, so the demosaic result is a uniform grey
/// and the only thing that can move a pixel is the curve. The colour matrix is
/// the identity and the balance is neutral for the same reason: this test is
/// about one stage, and a real body's matrix would make every assertion below
/// a statement about that body instead.
fn flat_raw(level: u16, curve: BaseCurve) -> RawImage {
RawImage {
width: SIZE,
height: SIZE,
data: vec![level; (SIZE * SIZE) as usize],
cfa_pattern: CfaPattern::Rggb,
black_level: [0; 4],
white_level: u16::MAX,
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: curve,
samples_per_pixel: 1,
profile: None,
make: String::new(),
model: String::new(),
crop: CropRect {
x: 0,
y: 0,
width: SIZE,
height: SIZE,
},
}
}
/// Render a neutral edit over a flat frame and return the centre pixel's red.
///
/// The centre rather than a corner: a demosaic has to invent its edges, and
/// the interpolated border of a 16×16 frame is not where anyone should be
/// reading a tone off.
fn rendered_level(ctx: &GpuContext, level: u16, curve: BaseCurve) -> u8 {
let raw = flat_raw(level, curve);
let source = Demosaicer::new(ctx)
.expect("demosaicer")
.run(&raw)
.expect("demosaic");
let shader = EditGraph::default_chain().compose();
let mut adjust = AdjustPass::new(ctx);
adjust.render(&source, &shader, SIZE, SIZE).expect("render");
let (pixels, _, _) = adjust.export_pixels().expect("readback");
let centre = ((SIZE / 2) * SIZE + SIZE / 2) * 4;
pixels[centre as usize]
}
/// The Canon EOS 6D's curve, from the shipped profile database.
///
/// Looked up by name rather than written out, so this also asserts the thing
/// no other test can: that a curve travels from the YAML, through the body
/// match, onto the decoded image and into the uniform block that the shader
/// actually reads.
fn six_d() -> BaseCurve {
let curve = dr_decode::base_curve::for_body("Canon", "EOS 6D");
assert!(
!curve.is_identity(),
"the shipped database must have a curve for the EOS 6D"
);
curve
}
#[test]
fn a_profiled_body_renders_brighter_midtones_than_a_flat_one() {
// **The whole requirement, in one assertion.** A linear midtone renders
// roughly half a stop dark, which is the flat, lifeless look FR-DEV-3e
// exists to get away from. If the curve did not reach the shader — wrong
// slot, wrong flag, wrong stage — this is the only test that would fail.
let Some(ctx) = ctx() else {
eprintln!("skipping: no GPU adapter");
return;
};
// 13% of full scale: roughly where a camera places middle grey, leaving
// about two and a half stops of highlight headroom above it.
let level = (0.13 * 65535.0) as u16;
let flat = rendered_level(&ctx, level, BaseCurve::IDENTITY);
let profiled = rendered_level(&ctx, level, six_d());
assert!(
profiled > flat + 8,
"the profile lifted middle grey from {flat} only to {profiled}"
);
}
#[test]
fn the_curve_leaves_black_black_and_white_white() {
// A base curve renders the range between the endpoints; it must not move
// the endpoints themselves. A curve that lifted black would put a grey
// veil over every night photograph, and one that pulled white down would
// make a correctly exposed frame look underexposed.
let Some(ctx) = ctx() else {
eprintln!("skipping: no GPU adapter");
return;
};
let curve = six_d();
assert_eq!(rendered_level(&ctx, 0, curve), 0, "black moved");
assert_eq!(rendered_level(&ctx, u16::MAX, curve), 255, "white moved");
}
#[test]
fn an_unprofiled_body_renders_exactly_as_it_did_before_profiles_existed() {
// The graceful fallback, asserted as a number rather than as a promise.
// With no curve the pipeline must still be a pass-through: black level
// out, white level in, sRGB encoding on the way to the screen and nothing
// else. "Never worse than today" is the one property this change was not
// allowed to trade away, and the way it would break is silently — a flag
// read from the wrong component would apply a curve nobody asked for.
let Some(ctx) = ctx() else {
eprintln!("skipping: no GPU adapter");
return;
};
for level in [0u16, 4_000, 8_520, 32_768, 60_000, u16::MAX] {
let scene = f32::from(level) / f32::from(u16::MAX);
let expected = (dr_types::Transfer::Srgb.encode(scene) * 255.0).round() as i32;
let got = i32::from(rendered_level(&ctx, level, BaseCurve::IDENTITY));
// Two 8-bit steps: the texture holding the demosaiced frame is
// `Rgba16Float`, so a value round-trips through eleven mantissa bits
// before it is encoded. That is well under one step at any level, and
// the tolerance is for the rounding either side of it rather than for
// the transform being approximate.
assert!(
(got - expected).abs() <= 2,
"raw {level} rendered as {got}, expected about {expected}"
);
}
}
#[test]
fn the_curve_is_monotone_through_the_whole_range() {
// The property the spline's tangent limiting exists to guarantee, checked
// where it actually matters: on the device, through the real uniform
// packing. A curve that dipped anywhere would put a dark band across a
// smooth gradient — a sky, most visibly — and it would read as a
// rendering fault rather than as a bad profile.
let Some(ctx) = ctx() else {
eprintln!("skipping: no GPU adapter");
return;
};
let curve = six_d();
let mut previous = 0u8;
for step in 0..=16u32 {
let level = (step * 65535 / 16) as u16;
let value = rendered_level(&ctx, level, curve);
assert!(
value >= previous,
"the curve fell from {previous} to {value} at raw level {level}"
);
previous = value;
}
}
core/dr-gpu/tests/film_sim.rs
+1 -2
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@@ -15,7 +15,7 @@
//! model is checked against the reference, and the shader is checked against
//! the CPU model.
use dr_decode::{BaseCurve, CfaPattern, CropRect, RawImage};
use dr_decode::{CfaPattern, CropRect, RawImage};
use dr_film::bake::{bake, Recipe, Settings};
use dr_gpu::{AdjustPass, Demosaicer, GpuContext, LabelField, MaskPass};
use dr_pipeline::mask::{MaskLayer, MaskSource};
@@ -48,7 +48,6 @@ fn flat_raw(level: u16) -> RawImage {
// Off deliberately: a film replaces the camera's rendering, and
// leaving a curve here would test the suppression rather than the
// film. `dr-pipeline` asserts the suppression on the generated source.
base_curve: BaseCurve::IDENTITY,
samples_per_pixel: 1,
profile: None,
make: String::new(),
core/dr-gpu/tests/hot_pixels.rs
+1 -2
View File
@@ -6,7 +6,7 @@
//! anything: the repair happens on the mosaic, and what a photographer would
//! see of a defect it missed is the coloured cross the demosaic makes of it.
use dr_decode::{BaseCurve, CfaPattern, CropRect, RawImage};
use dr_decode::{CfaPattern, CropRect, RawImage};
use dr_gpu::{AdjustPass, Demosaicer, GpuContext};
use dr_pipeline::EditGraph;
@@ -32,7 +32,6 @@ fn frame(pattern: CfaPattern, level: u16, set: &[(u32, u32, u16)]) -> RawImage {
white_level: WHITE,
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(),
core/dr-gpu/tests/view_transform.rs
+129
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@@ -0,0 +1,129 @@
//! TRACES: FR-DEV-3j | FR-DEV-2
//! The view transform, end to end on a device.
//!
//! `dr-pipeline` checks the curve on the CPU and that the composer emits it in
//! the right place. Neither would notice a shader that disagreed with the CPU
//! reference, or a clamp somewhere upstream that made two highlights the same
//! number before the curve ever saw them — which is exactly what the retired
//! base curve did, and why D19 exists. So this renders real pixels.
use dr_decode::{CfaPattern, CropRect, RawImage};
use dr_gpu::{AdjustPass, Demosaicer, GpuContext};
use dr_pipeline::view::Sigmoid;
use dr_pipeline::EditGraph;
const SIZE: u32 = 16;
fn ctx() -> Option<GpuContext> {
pollster::block_on(GpuContext::new_headless()).ok()
}
/// A flat RGGB frame at `level` out of 65535, with an identity matrix and a
/// neutral balance, so the only things that move a pixel are the edit and the
/// view transform.
fn flat_raw(level: u16) -> RawImage {
RawImage {
width: SIZE,
height: SIZE,
data: vec![level; (SIZE * SIZE) as usize],
cfa_pattern: CfaPattern::Rggb,
black_level: [0; 4],
white_level: u16::MAX,
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]),
samples_per_pixel: 1,
profile: None,
make: String::new(),
model: String::new(),
crop: CropRect {
x: 0,
y: 0,
width: SIZE,
height: SIZE,
},
}
}
/// Render `graph` over a flat frame and return the centre pixel's red.
///
/// The centre rather than a corner: a demosaic has to invent its edges.
fn rendered(ctx: &GpuContext, level: u16, graph: &EditGraph) -> u8 {
let source = Demosaicer::new(ctx)
.expect("demosaicer")
.run(&flat_raw(level))
.expect("demosaic");
let shader = graph.compose();
let mut adjust = AdjustPass::new(ctx);
adjust.render(&source, &shader, SIZE, SIZE).expect("render");
let (pixels, _, _) = adjust.export_pixels().expect("readback");
let centre = ((SIZE / 2) * SIZE + SIZE / 2) * 4;
pixels[centre as usize]
}
#[test]
fn the_shader_agrees_with_the_cpu_reference() {
// TRACES: FR-DEV-3j
let Some(ctx) = ctx() else {
eprintln!("skipping: no GPU adapter");
return;
};
let curve = Sigmoid::default_curve();
let graph = EditGraph::default_chain();
for level in [0u16, 500, 4_000, 8_520, 32_768, 60_000, u16::MAX] {
let scene = f32::from(level) / f32::from(u16::MAX);
let display = curve.channel(scene).min(1.0);
let expected = (dr_types::Transfer::Srgb.encode(display) * 255.0).round() as i32;
let got = i32::from(rendered(&ctx, level, &graph));
// Two 8-bit steps, for the `Rgba16Float` intermediate and the
// rounding either side of the encode.
assert!(
(got - expected).abs() <= 2,
"raw {level} rendered as {got}, expected about {expected}"
);
}
}
#[test]
fn highlights_above_one_stay_distinct() {
// TRACES: FR-DEV-2 | FR-DEV-3j
// The failure D19 names first. Two stops of exposure put these two
// frames at 1.0 and 1.5 of sensor saturation. The base curve was flat
// past 1.0, so both rendered as the same white; the view transform's
// shoulder still separates them.
let Some(ctx) = ctx() else {
eprintln!("skipping: no GPU adapter");
return;
};
let mut graph = EditGraph::default_chain();
graph.set_param(
dr_pipeline::ops::exposure::ID,
dr_pipeline::ops::exposure::EXPOSURE,
2.0,
);
let lower = rendered(&ctx, u16::MAX / 4, &graph);
let upper = rendered(&ctx, (u16::MAX / 8) * 3, &graph);
assert!(
upper > lower,
"scene 1.0 rendered {lower} and scene 1.5 rendered {upper}"
);
assert!(upper < 255, "scene 1.5 is below the default white point");
}
#[test]
fn the_rendering_is_monotone_through_the_whole_range() {
// TRACES: FR-DEV-3j
// A dip anywhere puts a dark band across a smooth gradient — a sky, most
// visibly.
let Some(ctx) = ctx() else {
eprintln!("skipping: no GPU adapter");
return;
};
let graph = EditGraph::default_chain();
let mut last = 0u8;
for step in 0..=32u32 {
let level = (step * u32::from(u16::MAX) / 32) as u16;
let got = rendered(&ctx, level, &graph);
assert!(got >= last, "raw {level} rendered {got}, below {last}");
last = got;
}
}