color-grading

name	color-grading
description	Color grade clips the way a professional colorist does — normalize, balance, match, then build a look — using inspect_color scopes and apply_color (exposure, white balance, wheels, curves, hue curves, LUTs). Use when the user asks to color, grade, match shots, fix white balance, fix exposure, neutralize a cast, or apply a look/film stock.

Grade in the colorist's order, scopes-first — never skip to a look, since a look on top of a cast just bakes it in. One apply_color call merges onto the current grade (only the params you pass change), so build up across calls and verify with inspect_color between stages. Ranges live in the reference tables below; prose names the knob, not the number.

Workflow

- [ ] 1. inspect_color — read scopes BEFORE touching anything
- [ ] 2. Normalize — exposure + white balance to neutral
- [ ] 3. Primary — black/white points, contrast, saturation
- [ ] 4. Match — pull each shot toward the reference (if matching)
- [ ] 5. Secondary — hue curves for skin/sky/foliage
- [ ] 6. Look — wheels split-tone and/or LUT
- [ ] 7. inspect_color again — confirm scopes moved as intended

1. Read first. inspect_color(clipId). Check luma.black/luma.white (near 0/1? clipLowPct/clipHighPct flag crush/clip), balance.warmCool + balance.greenMagenta (nonzero = a cast to neutralize), zones (where the cast lives), and hueHistogram12 (orange bins 1–2 = skin, cyan/blue bins 6–8 = sky).

2. Normalize. exposure for global brightness (prefer it over gamma). temperature to correct warmCool — higher = warmer, so lower it if too warm. tint to correct greenMagenta, pushing opposite the cast. Re-inspect: both balances near 0 before moving on.

3. Primary. blacks/whites to set the points, contrast + highlights/shadows to shape roll-off, saturation for overall sat — reach for vibrance instead when you want to boost muted color without clobbering skin.

4. Match shots. Grade the hero fully, then for each other shot call inspect_color(clipId, reference: <hero>), read the returned gap and its hints (e.g. "warmer than ref → cooler temperature"), apply the nudges, and repeat until the gap is small. Close it numerically — don't eyeball it.

5. Secondary. Adjust specific hues via hueCurves.targets (each targetHue affects ~±22°): hueShift rotates, satScale mutes/pops, lumShift darkens/brightens — e.g. deepen a sky without touching skin. Per-channel redCurve/greenCurve/blueCurve are tone-selective: tame a blown sky with blueCurve: [[0,0],[0.7,0.7],[1,0.85]].

6. Look. Split-tone with the wheels (*Hue+*Amount per zone, e.g. teal/orange = shadowsHue:210,shadowsAmount:0.2 + highsHue:30,highsAmount:0.15), add a film toe via masterCurve ([[0,0.06],[1,0.95]]), or fold in a lut:{path,strength} (.cube, absolute path; copied into project storage; pass strength alone to re-blend). For named stocks, build by hand — see Film looks below.

7. Confirm. Re-inspect_color: points near 0/1 without heavy clipping, neutral balance unless intentionally toned, skin in the orange bins.

apply_color reference

Merges onto the current grade; reset:true starts neutral. clipIds required (video/image only).

Group	Params	Range	Notes
Tone	exposure / contrast	−3…3 EV / 0.5–1.5	1 = neutral contrast
	highlights shadows blacks whites	−1…1	points & roll-off
White balance	temperature / tint	2000–11000 K / −100…100	higher = warmer; +tint green, −magenta
Saturation	saturation / vibrance	0–2 / −1…1	1 = neutral; vibrance protects skin
Wheels (per zone)	shadowsHue/midsHue/highsHue + matching *Amount	0–360° / 0–1	hue push + strength
	shadowsLum / midsGamma / highsGain	−0.5…0.5 / 0.5–2 / 0.5–1.5	per-zone brightness
Curves	masterCurve redCurve greenCurve blueCurve	[[x,y],…] 0–1	master preserves chroma
Hue curves	hueCurves.targets[] = {targetHue, hueShift, satScale, lumShift}	±30° / 0–2 / ±0.5	~±22° selectivity
LUT	lut = {path, strength}	strength 0–1	.cube, abs path

Hues: 0 red · 30 orange/skin · 60 yellow · 120 green · 180 cyan · 210 sky-blue · 240 blue · 300 magenta.

inspect_color(clipId | mediaRef, atFrame?, reference?) — clipId reads a clip's graded look, mediaRef a raw asset. Returns scopes (luma, meanRGB, zones, saturation, balance, hueHistogram12, colorfulPct) + the frame; with reference, also a gap and actionable hints (the backbone of shot matching).

Film looks (no LUT)

A LUT just freezes a set of curve/wheel/saturation moves — build any of them by hand, in this order:

1. Tone curve (toe + shoulder). The biggest tell: film never hits pure black or clips white. Lift the masterCurve toe and roll off its shoulder with gentle mid-S, e.g. [[0,0.04],[0.25,0.22],[0.75,0.82],[1,0.97]].
2. Per-channel crosstalk. Hue shifts with brightness — what separates real emulation from "S-curve + a tint." Lift the blue toe and pull its shoulder → teal shadows + warm highlights (blueCurve: [[0,0.05],[0.5,0.5],[1,0.92]]); nudge green mids for Fuji.
3. Split-tone the wheels (shadows→teal, highlights→amber).
4. Saturation sculpting — vibrance over flat saturation, plus hueCurves satScale to mute/boost individual hues.
5. Hue rotation — small hue-vs-hue shifts (≤8°): Kodak warms oranges, Fuji greens.

The recipes below are this method with the dials pre-set — apply onto an already-normalized clip, then re-inspect_color and tune toward the shot (scale *Amount and curve deviations toward neutral for less intensity). If the user has the real .cube, prefer lut:{path,strength:0.85}; these approximate a stock's character, not its science.

Kodak 2383 — Hollywood print (warm, contrasty; dense blacks, teal shadows, amber highlights):

{ "contrast": 1.25, "saturation": 1.15, "vibrance": 0.1, "temperature": 6800, "blacks": -0.1, "whites": 0.05,
  "shadowsHue": 195, "shadowsAmount": 0.12, "highsHue": 40, "highsAmount": 0.12, "masterCurve": [[0,0.02],[0.25,0.21],[0.75,0.83],[1,0.98]] }

Kodak 2389 — low-con print (clean, neutral; filmic roll-off, little tone):

{ "contrast": 1.08, "saturation": 1.03, "temperature": 6550, "blacks": -0.04, "highsHue": 45, "highsAmount": 0.06, "masterCurve": [[0,0.015],[0.3,0.29],[0.7,0.72],[1,0.99]] }

Fuji Eterna / 3513-like (soft, green-pastel; milky lifted blacks). The lifted toe is the signature — don't flatten it:

{ "contrast": 1.05, "saturation": 0.95, "vibrance": 0.12, "temperature": 6300, "blacks": 0.08, "shadows": 0.1, "highlights": -0.15, "whites": -0.04,
  "midsHue": 120, "midsAmount": 0.08, "shadowsHue": 185, "shadowsAmount": 0.1, "masterCurve": [[0,0.06],[0.25,0.27],[0.8,0.82],[1,0.95]] }

Kodak Portra — warm negative (soft, skin-flattering). The −tint + orange curve flatters skin — confirm the orange bins grew, not the reds:

{ "contrast": 1.05, "saturation": 1.0, "vibrance": 0.15, "temperature": 6900, "tint": -3, "blacks": 0.06, "highlights": -0.1, "highsHue": 38, "highsAmount": 0.08,
  "hueCurves": { "targets": [ { "targetHue": 30, "satScale": 1.08, "hueShift": -4 } ] } }

Bleach bypass (desaturated, high-contrast, metallic). Scale saturation 0.4–0.7 for intensity:

{ "contrast": 1.35, "saturation": 0.55, "temperature": 6300, "tint": 5, "blacks": -0.15, "whites": 0.1, "masterCurve": [[0,0.0],[0.2,0.13],[0.8,0.9],[1,1.0]] }

Teal & orange — blockbuster (cool shadows, warm skin). Keep the orange curve modest so faces don't go radioactive:

{ "contrast": 1.2, "saturation": 1.1, "vibrance": 0.15, "shadowsHue": 210, "shadowsAmount": 0.2, "highsHue": 30, "highsAmount": 0.15,
  "hueCurves": { "targets": [ { "targetHue": 30, "satScale": 1.15 } ] } }

Vintage / faded (milky blacks, low sat, warm-yellow age). The high toe is the whole look — blacks never reach 0:

{ "contrast": 0.95, "saturation": 0.8, "temperature": 6700, "tint": 4, "blacks": 0.12, "highlights": -0.1, "masterCurve": [[0,0.1],[0.5,0.52],[1,0.92]] }

Notes

• apply_color is the colorist path and folds in LUT + curves + hue curves as live, editable effects. apply_effect is for generic, non-color FX — don't grade with it.
• get_timeline exposes each graded clip's color object in the same vocabulary — pass that object as apply_color({ clipIds, color }) to copy a whole grade (replaces; mutually exclusive with knobs/reset).
• Mutations return timeline deltas (including updated color) — patch from those; don't re-read the whole timeline after every nudge.
• Trust scopes over the preview for balance — monitors and JPEGs lie about subtle casts; use the frame for composition/look judgment.
• lumShift is an additive HSV value shift in display space, not a linear luma divide, so per-hue darkening won't amplify shadow macroblocks.
• Curve points are piecewise-linear, clamped flat outside their range — include endpoints near [0,0]/[1,1] unless you mean to clip.