Stop describing a base curve the pipeline no longer has

D19 retired the per-body base curve, moved the matrix ahead of the
edits and the film into the view transform's place, but a dozen doc
comments still listed the curve among what a pixel passes through, or
said the film skipped it. The detail stage's module doc still drew the
matrix after the edits and the last detail pass encoding, which the
view pass took over. The film crate's README gave the base curves as
its reason for being data, and the ops README's list of hand-written
nodes had neither the view transform nor three of the five kernels.

FR-MRG-2 gave the base curve as why the merge cuts below the profile;
the view transform is why now. The decision table still said colour
defaults were a per-body curve, and FR-DEV-3j said only the default
view transform skips a JPEG, where the node skips one whatever its
sliders say. frame-budget.md records the view pass as unmeasured.

core/dr-decode/src/profile.rs

@@ -67,8 +67,8 @@
 //! FR-DEV-3e defers full `.dcp` support — `HueSatDeltas` and
 //! `ProfileLookTable` — and requires that they arrive as *additions* rather
 //! than as a pipeline reordering. They would: both are lookups applied to a
-//! colour after this matrix and before, or alongside, the base curve, so they
-//! extend [`CameraProfile`] with more calibration data and extend the shader's
+//! colour at this matrix, before any edit reaches it, so they extend
+//! [`CameraProfile`] with more calibration data and extend the shader's
 //! camera-profile stage with more work. Nothing above would move.
 
 use crate::{cam_to_srgb_from, invert3};

core/dr-film/README.md

@@ -1,9 +1,8 @@
 # Film stocks
 
 One file per stock in [`profiles/`](profiles/). Adding a stock is adding a
-file — no code change, no shader, no new operation — for the same reason
-`dr-decode`'s base curves work that way: under the GPLv3 a stock should be
-contributable without a release.
+file — no code change, no shader, no new operation — because under the GPLv3
+a stock should be contributable without a release.
 
 ## What a profile is
 
@@ -51,6 +50,13 @@ matters — see [`src/bake.rs`](src/bake.rs) for the argument:
    log exposure through the negative, the enlarger's exposure is added there,
    and the paper's own curve row and cube take it to linear sRGB.
 
+The stock is the last thing that happens to the picture. It runs in the view
+transform's place (D19): handed linear sRGB, scene-referred, after every other
+adjustment and after sharpening and noise reduction, and handing back the
+rendering the output transform encodes. So every other slider decides the
+exposure the negative receives, and the default tone mapping is not applied
+on top.
+
 Per pixel that is a matrix multiply, a handful of curve taps and one texture
 fetch — two for a print. Splitting 2 from 3, rather than baking one LUT over exposure, is measured
 rather than assumed: the curve carries all the sharp shape and the dye mixing

core/dr-gpu/src/adjust.rs

@@ -1520,9 +1520,9 @@ impl AdjustPass {
     /// one: the storage format is in the layout. The profile uniforms are
     /// filled neutral here rather than from the source, which is the whole
     /// point of the mode (`OutputMode::CameraLinear`): unit white balance,
-    /// identity matrix, base curve off. The non-linear flag is kept, so a
-    /// JPEG source is still linearised — camera space for a JPEG is the
-    /// decoded values made linear, which is the best that exists.
+    /// identity matrix, and no view transform composed. The non-linear flag
+    /// is kept, so a JPEG source is still linearised — camera space for a
+    /// JPEG is the decoded values made linear, which is the best that exists.
     ///
     /// The texture stays on the device for a merge's warp to sample; see
     /// [`Self::camera_texture`] and [`Self::read_camera_linear`].

core/dr-gpu/src/demosaic.rs

@@ -320,10 +320,11 @@ impl DemosaicedImage {
             color_matrix: IDENTITY_3X3,
             as_shot_wb: [1.0, 1.0, 1.0],
             // **The identity, and this is the whole reason the field is here
-            // rather than resolved further down.** A JPEG has already had its
-            // camera's base curve baked in by the camera; applying one again
-            // would render the rendering, crushing the shadows and flattening
-            // the highlights of an image that was already finished.
+            // rather than resolved further down.** A JPEG has already been
+            // rendered by the camera; the view transform skips a source
+            // flagged non-linear, since rendering the rendering would crush
+            // the shadows and flatten the highlights of an image that was
+            // already finished.
             non_linear: true,
             id: next_image_id(),
             frame: (width, height),
@@ -338,7 +339,7 @@ impl DemosaicedImage {
     /// what a merge writes. No demosaic; the samples are normalised by the
     /// file's black and white levels exactly as the demosaic kernel would
     /// normalise a photosite, and everything else — the matrix, the
-    /// balance, the body's base curve — is carried through as for a CFA
+    /// balance, the view transform — is carried through as for a CFA
     /// file, because the composite is developed as one photograph from the
     /// body that took its sources.
     pub fn from_linear_rgb16(ctx: &GpuContext, raw: &RawImage) -> Result<Self, GpuError> {

core/dr-gpu/src/raw_histogram.rs

@@ -28,8 +28,8 @@
 //! than leaving the specification and the code silently disagreeing.
 //!
 //! That texture is the right one on the merits. It is camera-native: no white
-//! balance has been applied, no camera matrix, no base curve, no tone curve,
-//! no output transform. It is normalised by the sensor's own black and white
+//! balance has been applied, no camera matrix, no tone curve, no view
+//! transform, no output transform. It is normalised by the sensor's own black and white
 //! levels, so 1.0 is saturation by construction and the distribution below it
 //! *is* the headroom question, with no calibration to carry and no origin to
 //! choose.

core/dr-gpu/src/shaders/raw_histogram.wgsl

@@ -3,7 +3,7 @@
 //
 // The shader beside this one, `histogram.wgsl`, counts the frame the display
 // is about to show: an 8-bit code value, after white balance, the camera
-// matrix, the base curve, the tone curve and the output transform. This one
+// matrix, the tone curve, the view transform and the output transform. This one
 // counts the texture the demosaic wrote, before any of that. The two differ in
 // exactly one place — the axis — and everything else here is deliberately the
 // same construction, because the two reductions have the same shape and any

core/dr-pipeline/ops/README.md

@@ -228,9 +228,11 @@ interpolated points — master, red, green, blue — each reaching the shader on
 when it has been moved), `colour_mixer` (thirty-six faceted parameters from
 twelve computed hue bands), `film_sim` (a stock's measured tables, which are
 not parameters, and the one node that declares `Operation::renders` — see
-below), `capture_sharpen` (a separable convolution) and `noise_reduction` (a
-kernel, and one that decides how many dispatches to emit at each resolution) —
-the last two for the reason the next section gives. `vignetting` is
+below), `view_transform` (composed at its defaults, which a declaration cannot
+say — see [What is not a node](#what-is-not-a-node-and-why)), and the five
+kernels — `capture_sharpen` (a separable convolution), `noise_reduction` (one
+that decides how many dispatches to emit at each resolution), `clarity`,
+`texture` and `dehaze` — for the reason the next section gives. `vignetting` is
 hand-written too but is not in the develop chain — it carries lens-profile
 coefficients that are not parameters.
 
@@ -262,7 +264,8 @@ clarity, texture, dehaze and spot removal are all defined by what the
 of `c` at any price.
 
 They go in the **detail stage**, which runs after the fused pass, in linear
-light, at render resolution, before the output transform — see
+light, at render resolution, before the view transform and the output
+transform — see
 [`../src/detail.rs`](../src/detail.rs) for why each of those is a decision
 rather than a convenience. A node of this kind:
 

core/dr-pipeline/ops/film_sim.yaml

@@ -11,8 +11,8 @@ why_rust: |
   characteristic curves and a density lookup — which are not parameters and
   which no `uniforms:` expression could produce. Its neutral is "no stock
   loaded" rather than a set of values, and it is the one node that declares
-  `Operation::renders`, so the composer omits the camera profile's base curve
-  and the conversion out of camera space on its behalf.
+  `Operation::renders`, so while a stock is loaded the composer emits it in
+  the view transform's place instead of the default sigmoid.
 
 placement: |
   Last, in the view transform's place (D19, FR-DEV-3j), after every other

core/dr-pipeline/src/descriptor.rs

@@ -659,10 +659,10 @@ impl Attribute {
     ///
     /// `Effect` after `Colour` is a look laid over a settled picture — and is
     /// the one arguable slot. A spectral film simulation declares
-    /// [`crate::Operation::renders`] and replaces the base curve, which is an
-    /// argument for treating it as foundational rather than final; an array of
-    /// six cannot say "last, except when it is first". The tension is recorded
-    /// here rather than settled.
+    /// [`crate::Operation::renders`] and takes the view transform's place at
+    /// the very end of the chain (D19), which is an argument for treating it as
+    /// the rendering rather than one effect among others; an array of six
+    /// cannot say that. The tension is recorded here rather than settled.
     ///
     /// Both ends were wrong for as long as this list only fed a row of chips
     /// nobody reads in order. It stopped being harmless when the same list

core/dr-pipeline/src/detail.rs

@@ -24,9 +24,10 @@
 //!        v
 //!   +------------------------------------------+
 //!   | the fused point-operation pass           |  one dispatch
-//!   |   white balance, exposure, tone, colour  |
-//!   |   the mask layers                        |
+//!   |   white balance (camera RGB)             |
 //!   |   camera RGB -> linear sRGB              |
+//!   |   exposure, tone, colour                 |
+//!   |   the mask layers                        |
 //!   +------------------------------------------+
 //!        |  rgba16float, linear, **unclipped**, at render resolution
 //!        v
@@ -34,7 +35,13 @@
 //!   | the detail stage - this module           |  one dispatch per pass
 //!   |   sharpen, NR, clarity, texture, spots   |
 //!   +------------------------------------------+
-//!        |  the last pass applies the output transform
+//!        |  rgba16float, still scene-linear and unclipped
+//!        v
+//!   +------------------------------------------+
+//!   | the view pass                            |  one dispatch
+//!   |   view transform, or the film stock      |
+//!   |   output transform, mask reveal          |
+//!   +------------------------------------------+
 //!        v
 //!   rgba8unorm display or export texture
 //! ```
@@ -52,14 +59,13 @@
 //! texture, clarity, spot removal and sharpen/NR sit below the tone curve and
 //! the colour mixer.
 //!
-//! **In linear light, after the camera matrix.** The fused pass works in
-//! *camera* space, because white balance and exposure are physically
-//! meaningful there and nowhere else. A detail pass is the opposite case: it
-//! wants a luminance, and camera RGB has no luminance — the three channels are
+//! **In linear light, after the camera matrix.** A detail pass wants a
+//! luminance, and camera RGB has no luminance — the three channels are
 //! whatever the CFA's dyes passed, and weighting them 0.2126/0.7152/0.0722
-//! would be numerology. So the split is taken *after* the `cam_to_srgb`
-//! multiply, where the working space is linear sRGB and a luminance is a
-//! luminance.
+//! would be numerology. Since D19 only white balance runs in camera RGB; the
+//! `cam_to_srgb` multiply follows it, so every point operation, and every
+//! detail pass after them, works in linear sRGB primaries, where a luminance
+//! is a luminance.
 //!
 //! **Before the output transform, and before the clip.** FR-DEV-2 allows
 //! exactly one quantisation, at the display or export stage. A detail pass
@@ -70,9 +76,11 @@
 //! therefore `rgba16float` and holds linear values that have **not** been
 //! clamped to `0..=1`: a recovered highlight is still above one at this point,
 //! and clipping it before the sharpener sees it would put a hard edge exactly
-//! where the sharpener is most visible. The last detail pass performs the
-//! primaries conversion, the clip and the encode, so the single quantisation
-//! stays single.
+//! where the sharpener is most visible. Every detail pass writes such an
+//! intermediate, the last one included, and the view pass after them — the
+//! view transform, then the output transform's primaries, clip and encode —
+//! is the one place the scene is fitted to a display (D19, ARCH §6.14), so
+//! the single quantisation stays single.
 //!
 //! **After framing, at render resolution.** The alternative — running detail
 //! on the demosaiced source before the framing prologue — is superficially

core/dr-pipeline/src/mask.rs

@@ -2068,8 +2068,8 @@ pub(crate) struct LayerShader {
     ///
     /// Kept apart from the rest because it belongs at the other end of the
     /// shader. Everything else runs on scene-referred colour in the working
-    /// space, where a flat tint would then be pushed through the base curve
-    /// and the camera matrix and arrive as some other colour, and a
+    /// space, where a flat tint would then be pushed through the view
+    /// transform and arrive as some other colour, and a
     /// white-on-black alpha would arrive as neither. This runs after the
     /// output transform, so what is written is what is seen.
     pub reveal: String,

core/dr-pipeline/src/neutral.rs

@@ -82,8 +82,8 @@ const FLOOR: f32 = 1e-4;
 /// Move the graph so that `sample` renders neutral.
 ///
 /// `sample` is the linear triple the operation's own gains multiply — camera
-/// RGB with the camera's as-shot balance on, *before* the body's base curve
-/// and matrix, and with the sampling operation at its defaults. Not the
+/// RGB with the camera's as-shot balance on, *before* the camera matrix and
+/// the view transform, and with the sampling operation at its defaults. Not the
 /// pixel on the screen: the matrix mixes the channels on the way there, so
 /// a colour read after it does not answer to these gains, and a solve over
 /// one lands somewhere no sample asked for. Returns whether the graph was

core/dr-pipeline/src/operation.rs

@@ -518,7 +518,7 @@ pub enum OutputMode {
     ///
     /// What a merge stitches (FR-MRG-2). The shader is the linear tail with
     /// no operations, and the caller fills the reserved uniforms neutral —
-    /// unit white balance, identity matrix, base curve off — so what is
+    /// unit white balance, identity matrix, no view transform — so what is
     /// stored is the sensor's own numbers, demosaiced and undistorted. Only
     /// [`compose_camera_probe`] produces it — for a merge through
     /// [`compose_camera_linear`], and for the white balance picker under the

core/dr-pipeline/src/ops/film_sim.rs

@@ -706,10 +706,10 @@ mod tests {
 
     #[test]
     fn it_declares_itself_a_rendering_transform() {
-        // The whole reason the composer skips the base curve and the camera
-        // matrix. If this ever returned false the picture would be rendered
-        // twice and converted twice, which looks like a colour management bug
-        // a long way from here.
+        // The whole reason the composer emits the stock in the view
+        // transform's place rather than beside it. If this ever returned
+        // false the picture would be rendered twice, which looks like a
+        // colour management bug a long way from here.
         assert!(FilmSim::new().renders());
     }