Sync with integration

core/dr-pipeline/ops/README.md

@@ -209,11 +209,12 @@ They still belong in this directory, because the pipeline's **order** is the
 one thing a reader comes here to learn, and an order written half in YAML and
 half in Rust would be worse than either alone.
 
-Currently hand-written: `tone_curve` (a curve widget over five interpolated
-points), `colour_mixer` (thirty-six faceted parameters from twelve computed hue
-bands), `capture_sharpen` (a separable convolution, which is the other reason a
-node is Rust — see the next section). `vignetting` is hand-written too but is
-not in the develop chain — it
+Currently hand-written: `tone_curve` (one widget over four curves of five
+interpolated points — master, red, green, blue — each reaching the shader only
+when it has been moved), `colour_mixer` (thirty-six faceted parameters from
+twelve computed hue bands), `capture_sharpen` (a separable convolution, which
+is the other reason a node is Rust — see the next section). `vignetting` is
+hand-written too but is not in the develop chain — it
 carries lens-profile coefficients that are not parameters. `distortion` and
 `aberration` are `Warp`s rather than operations: they rewrite coordinates
 before sampling rather than transforming a colour after it.