diff --git a/crates/effects/src/color2.rs b/crates/effects/src/color2.rs index d78b0fb0..9547fd77 100644 --- a/crates/effects/src/color2.rs +++ b/crates/effects/src/color2.rs @@ -55,6 +55,17 @@ impl Curve { /// Parse "x,y x,y …" (separators: whitespace or ';'). Returns None for an identity curve or /// fewer than two valid points. pub fn parse(s: &str) -> Option { + Self::parse_with(s, false) + } + + /// [`Curve::parse`] interpolated as After Effects' Curves effect does: a natural cubic spline + /// through the points, clamped to 0..1 (AE 2026: RGB points (0,0) (125,199) (255,255) and + /// Red (0,0) (128,44) (255,255) map every grey step exactly as the natural spline does). + pub fn parse_natural(s: &str) -> Option { + Self::parse_with(s, true) + } + + fn parse_with(s: &str, natural: bool) -> Option { let mut pts: Vec<(f32, f32)> = s .split(|c: char| c.is_whitespace() || c == ';') .filter(|t| !t.is_empty()) @@ -74,6 +85,12 @@ impl Curve { let ys: Vec = pts.iter().map(|p| p.1).collect(); let n = xs.len(); let d: Vec = (0..n - 1).map(|k| (ys[k + 1] - ys[k]) / (xs[k + 1] - xs[k])).collect(); + if natural { + let ms = natural_slopes(&xs, &d); + let mut c = Curve { xs, ys, ms, lut: Vec::new() }; + c.lut = (0..=LUT_N).map(|i| c.eval_exact(i as f32 / LUT_N as f32).clamp(0.0, 1.0)).collect(); + return Some(c); + } let mut ms = vec![0.0f32; n]; ms[0] = d[0]; ms[n - 1] = d[n - 2]; @@ -136,6 +153,40 @@ impl Curve { } } +/// Knot slopes of the natural cubic spline (zero curvature at both ends) through points with +/// abscissae `xs` and segment slopes `d`; as Hermite tangents they reproduce the spline exactly. +fn natural_slopes(xs: &[f32], d: &[f32]) -> Vec { + let n = xs.len(); + if n < 3 { + return vec![d.first().copied().unwrap_or(0.0); n]; + } + let h: Vec = (0..n - 1).map(|k| f64::from(xs[k + 1] - xs[k])).collect(); + let dd: Vec = d.iter().map(|&v| f64::from(v)).collect(); + // Second derivatives M[1..n-1] (M[0] = M[n-1] = 0): tridiagonal system, Thomas algorithm. + let m = n - 2; + let (mut a, mut b, mut c, mut r) = (vec![0.0; m], vec![0.0; m], vec![0.0; m], vec![0.0; m]); + for i in 0..m { + let k = i + 1; + a[i] = h[k - 1]; + b[i] = 2.0 * (h[k - 1] + h[k]); + c[i] = h[k]; + r[i] = 6.0 * (dd[k] - dd[k - 1]); + } + for i in 1..m { + let w = a[i] / b[i - 1]; + b[i] -= w * c[i - 1]; + r[i] -= w * r[i - 1]; + } + let mut sec = vec![0.0f64; n]; + for i in (0..m).rev() { + let next = if i + 1 < m { sec[i + 2] } else { 0.0 }; + sec[i + 1] = (r[i] - c[i] * next) / b[i]; + } + let mut ms: Vec = (0..n - 1).map(|k| (dd[k] - h[k] * (2.0 * sec[k] + sec[k + 1]) / 6.0) as f32).collect(); + ms.push((dd[n - 2] + h[n - 2] * (sec[n - 2] + 2.0 * sec[n - 1]) / 6.0) as f32); + ms +} + fn ev(c: &Option, v: f32) -> f32 { c.as_ref().map(|c| c.eval(v)).unwrap_or(v) } @@ -145,7 +196,7 @@ fn ev(c: &Option, v: f32) -> f32 { /// sorted on load); the default `"0,0 1,1"` is the identity. Colour channels go through the /// master RGB curve first, then their own curve. fn curves(ctx: &EffectCtx, mut b: Buf) -> Buf { - let [m, r, g, bl, a] = ["rgb", "red", "green", "blue", "alpha"].map(|id| Curve::parse(ctx.params.s(id))); + let [m, r, g, bl, a] = ["rgb", "red", "green", "blue", "alpha"].map(|id| Curve::parse_natural(ctx.params.s(id))); if m.is_none() && r.is_none() && g.is_none() && bl.is_none() && a.is_none() { return b; } @@ -1199,6 +1250,29 @@ mod tests { assert!((clipped.get(0, 0)[0] - 0.05).abs() < 1e-5, "{:?}", clipped.get(0, 0)); } + /// After Effects 2026 (cases 962 / 963): Curves through RGB (0,0) (125,199) + /// (255,255) and Red (0,0) (128,44) (255,255) on grey steps 0..255, 8-bit results. + #[test] + fn curves_follow_a_natural_spline_as_in_after_effects() { + let steps = [0u8, 16, 32, 64, 96, 128, 160, 192, 224, 255]; + let mut img = Image::new(10, 1); + for (x, v) in steps.iter().enumerate() { + let v = *v as f32 / 255.0; + img.set(x as u32, 0, [v, v, v, 1.0]); + } + let p = |pts: &[(f32, f32)]| Value::Str(pts.iter().map(|(x, y)| format!("{},{}", x / 255.0, y / 255.0)).collect::>().join(" ")); + let rgb = run("ec.color.curves", &img, &[("rgb", p(&[(0.0, 0.0), (125.0, 199.0), (255.0, 255.0)]))]); + let red = run("ec.color.curves", &img, &[("red", p(&[(0.0, 0.0), (128.0, 44.0), (255.0, 255.0)]))]); + let ae_rgb = [0, 30, 59, 115, 164, 202, 227, 242, 250, 255]; + let ae_red = [0, 0, 1, 6, 19, 44, 83, 135, 194, 255]; + for x in 0..10 { + let g = (rgb.get(x as i64, 0)[1] * 255.0).round() as i32; + let r = (red.get(x as i64, 0)[0] * 255.0).round() as i32; + assert!((g - ae_rgb[x]).abs() <= 1, "RGB step {}: {g} vs AE {}", steps[x], ae_rgb[x]); + assert!((r - ae_red[x]).abs() <= 1, "Red step {}: {r} vs AE {}", steps[x], ae_red[x]); + } + } + #[test] fn levels_ic_identity_and_red_only() { let img = ramp(); diff --git a/crates/gpu/src/effects.rs b/crates/gpu/src/effects.rs index 42d2bab7..33deb36a 100644 --- a/crates/gpu/src/effects.rs +++ b/crates/gpu/src/effects.rs @@ -388,7 +388,7 @@ fn transform(e: &mut Enc, ctx: &EffectCtx, mut b: GBuf) -> Option { // ---------------------------------------------------------------- per-pixel fn curves(e: &mut Enc, ctx: &EffectCtx, b: GBuf) -> Option { - let parsed = ["rgb", "red", "green", "blue", "alpha"].map(|id| effectcraft_effects::Curve::parse(ctx.params.s(id))); + let parsed = ["rgb", "red", "green", "blue", "alpha"].map(|id| effectcraft_effects::Curve::parse_natural(ctx.params.s(id))); if parsed.iter().all(Option::is_none) { return Some(b); } diff --git a/docs/effects-parity.md b/docs/effects-parity.md index 4e9a2ddb..099e783e 100644 --- a/docs/effects-parity.md +++ b/docs/effects-parity.md @@ -30,7 +30,7 @@ corpus compares renders, each effect is assumed to differ somewhere, and users k | Audio | 13 | 0 | CPU by design (applied in the mixdown) | | Blur & Sharpen | 16 | 15 | Gaussian Blur interaction and output to be measured first ([fidelity/ae-2026-acceptance.md](fidelity/ae-2026-acceptance.md)) | | Channel | 13 | 13 | — | -| Color Correction | 40 | 40 | Tint, Tritone and Black & White (sliders and Tint) match After Effects 2026 renders (Rec. 601 luminance); Levels (Individual Controls) matches After Effects 2026 in 32 bpc (channel controls before RGB, "Off for 32 bpc Color" unclipped; plain Levels' channel order not measured); Brightness & Contrast (non-legacy) within about 6/255 of After Effects 2026 ramps (negative settings invert the positive curves); Tint has Swap Colors (#963); ACES 2.0 / OCIO 2.5 (26.5); Apply Color LUT (#514) and 32-bpc blending (#494) are closed | +| Color Correction | 40 | 40 | Tint, Tritone and Black & White (sliders and Tint) match After Effects 2026 renders (Rec. 601 luminance); Levels (Individual Controls) matches After Effects 2026 in 32 bpc (channel controls before RGB, "Off for 32 bpc Color" unclipped; plain Levels' channel order not measured); Brightness & Contrast (non-legacy) within about 6/255 of After Effects 2026 ramps (negative settings invert the positive curves); Curves interpolates a natural cubic spline through its points, as After Effects 2026 (exact on its grey steps); Tint has Swap Colors (#963); ACES 2.0 / OCIO 2.5 (26.5); Apply Color LUT (#514) and 32-bpc blending (#494) are closed | | Distort | 39 | 35 | Liquify has no viewer brush; #303 (Mesh Warp drag) and #534 (CC Power Pin Unstretch) are closed | | Expression Controls | 9 | 9 | — | | Generate | 26 | 25 | 4-Color Gradient's Blend matches After Effects 2026 (weights 1 / (d² + Blend²)); Fill's Opacity is the filled layer's opacity, as After Effects 2026 renders it (with a Fill Mask it still mixes with the original, not measured); Fractal on the CPU (needs f64); #526 (Reset) and #536 (Write-on marks) are closed | @@ -72,6 +72,7 @@ the GPU is performance, not parity. | 2026-10-19 | minor | Luma Key and Extract: Rec. 601 luminance (was Rec. 709), measured against After Effects 2026 (CPU and GPU) | | 2026-10-19 | minor | 4-Color Gradient: each point weighs 1 / (d² + Blend²), measured against After Effects 2026 at Blend 10 / 50 / 100 / 300 (CPU and GPU) | | 2026-10-19 | minor | Fill without a mask: the layer becomes the fill colour at its alpha × Opacity (was a mix with the original), measured against After Effects 2026 (CPU and GPU) | +| 2026-10-19 | minor | Curves: natural cubic spline through the points, clamped to 0..1 (was a monotone spline), measured against After Effects 2026 (CPU and GPU); Lumetri's curves and Glow's Arbitrary Map keep the monotone spline | | 2026-10-18 | minor | Tint uses Rec. 601 luminance weights, measured against After Effects 2026 renders of red, green, blue and grey solids (CPU and GPU) | | 2026-10-18 | minor | Exposure converts to linear light with a pure 2.2 power curve, as measured in After Effects (Offset 0.0005 / 0.002 / 0.02 / 0.1 on black: 8 / 15 / 43 / 90), not the piecewise sRGB curve; its sliders take After Effects' ranges (Exposure −100..100, slider −4..4; Offset −2..2, slider −0.5..0.5; Gamma Correction 0.1..10) | | 2026-10-12 | minor | Parameters 3,014 to 3,017 (effects.md); #303, #514, #526, #533–#536 marked closed instead of pending |