color-motion

name	color-motion
description	This skill should be used when the user asks to "build a color palette for a motion piece", "make a gradient background", "animate a color transition", "interpolate colors smoothly", "fix muddy/gray gradients", "convert colors to OKLCH", "color-grade a video for mood", "fix washed-out After Effects renders", "gamma shift", "Rec.709 vs sRGB", "colors shifted after rendering", or "match preview to final video". Covers palette construction, gradients, perceptual interpolation (OKLCH/Lab), grading order, and video/render color management.
version	0.1.0

Color in Motion

Choose, pair, and animate color for motion design: building restrained palettes, constructing gradients that read as premium, interpolating colors in perceptually-uniform spaces, and grading a piece for mood and consistency. Produces palettes with exact OKLCH/hex values, gradient CSS/code, and transition parameters.

When to use

• Picking or pairing a palette for a motion or video piece.
• Building gradient backgrounds (mesh, noise, animated drift).
• Animating color transitions (button states, theme switch, loaders).
• Grading a video for mood, or fixing dull/gray gradient interpolation.
• Fixing washed-out, gamma-shifted, or platform-inconsistent After Effects renders, and choosing correct per-platform export/color tags.

Core techniques

1. Build a restrained palette

Limit hues. A strong motion palette is 1 primary + 1 accent + 2-3 neutrals. Derive contrast and depth from lightness and chroma, not from adding more hues. Extra hues fight for attention and read as amateur.

In dark scenes, make the accent pop with low-to-moderate chroma and high lightness rather than maximum saturation — a blown-out saturated accent vibrates and looks cheap on dark backgrounds.

Use OKLCH to reason about color: oklch(L C H) where L is perceptual lightness (0-1), C is chroma (0 ≈ 0.37 max), H is hue angle (0-360). Holding L and C constant while rotating H gives hues of genuinely equal visual weight — impossible to do reliably in HSL.

Primary:   oklch(0.62 0.19 264)   /* confident blue */
Accent:    oklch(0.78 0.17 50)    /* warm amber, lighter so it pops */
Neutral-0: oklch(0.97 0.005 264)  /* near-white, faint hue tint */
Neutral-1: oklch(0.55 0.01 264)
Neutral-2: oklch(0.18 0.015 264)  /* near-black, same hue family */

Tinting neutrals slightly toward the primary hue (tiny chroma) unifies the frame; pure gray neutrals next to colored elements look disconnected.

2. Interpolate in OKLCH or Lab — never raw sRGB

Linearly interpolating two colors in sRGB passes through a desaturated, often gray or muddy midpoint (blue->yellow goes through gray; blue->red through muddy purple). Perceptual spaces (OKLCH, OKLab, CIE Lab) keep midpoints vivid and lightness even.

CSS gradients support this natively:

/* Vivid, even midpoint */
background: linear-gradient(in oklch, #2b6cff, #ffb02e);

/* Control hue path around the wheel for two-stop gradients */
background: linear-gradient(in oklch longer hue, #2b6cff, #ffb02e);
background: conic-gradient(in oklch, red, blue, red);

For animated transitions interpolate with a library (see references) and emit per-frame colors, or for two-color CSS transitions register a typed custom property so the browser interpolates in the chosen space.

3. Gradients that read as premium

• Mesh / multi-radial: stack several radial-gradients at different positions over a base color. Soft, organic, expensive-looking.
• Add grain: a faint noise overlay (SVG feTurbulence or a tiled PNG at ~3-5% opacity) kills banding and adds texture.
• Animate slowly: drift gradient positions over 8-20s with ease-in-out alternate. Slow is premium; fast gradient motion looks like a screensaver.

.mesh {
  background-color: #0b0f1a;
  background-image:
    radial-gradient(at 20% 25%, oklch(0.62 0.19 264 / 0.7), transparent 50%),
    radial-gradient(at 80% 30%, oklch(0.70 0.16 320 / 0.6), transparent 55%),
    radial-gradient(at 50% 85%, oklch(0.78 0.17 50  / 0.5), transparent 50%);
  animation: drift 16s ease-in-out infinite alternate;
}
@keyframes drift {
  to { background-position: 8% -6%, -8% 6%, 4% 8%; }
}

4. Color transition animation

Inline timing essentials so this skill stands alone: enter/highlight with ease-out (cubic-bezier(0.16, 1, 0.3, 1)), state changes 150-300ms, theme/full-screen washes 400-800ms. Use linear only for continuous loops.

@property --c { syntax: "<color>"; initial-value: #2b6cff; inherits: false; }
.btn { background: var(--c); transition: --c 200ms cubic-bezier(0.16,1,0.3,1); }
.btn:hover { --c: #ffb02e; }

@property registration is what makes the color actually interpolate (unregistered custom properties jump instantly).

5. Grade for mood — correct order

Apply grading operations in this order; reordering changes the result:

1. Exposure / white balance — fix overall brightness and neutralize/intentionally set the cast first.
2. Contrast — set black and white points; expand or compress the tonal range.
3. Midtones / saturation — adjust overall saturation and midtone color.
4. Split-tone — tint shadows and highlights separately. The classic cinematic look is teal shadows + orange highlights (complementary, flatters skin). Keep it subtle.
5. Unify — a final overall tint/LUT and a subtle vignette to bind the frame.

In code, grade by chaining CSS filters or a fragment shader; for video, an actual LUT or grading panel. Always grade the whole piece consistently so shots cut together.

6. Video / render color management

When a render looks correct in the After Effects comp viewer but washed-out, too bright, milky, or gamma-shifted in QuickTime, a browser, or across macOS/Windows, the cause is a gamma/transfer mismatch across four stages — AE working space, the render's embedded tag, the player's interpretation, and the display/OS gamma — not the artwork.

Core rules:

• Set an explicit working space. File > Project Settings > Color tab: Working Space = Rec.709 Gamma 2.4 for SDR video (or sRGB for UI/stills); "None" disables color management and the viewer lies about the final look. Set Depth to 16 bpc for grades/gradients to avoid banding.
• Rec.709 vs sRGB. They share primaries but differ in transfer (sRGB ~2.2 piecewise vs Rec.709 display 2.4 / BT.1886). Using the wrong one shifts midtone brightness — Rec.709 for video, sRGB for screenshots/PNG/UI.
• Embed a color tag on export. The shift across macOS/Windows/players comes from untagged files; each player guesses its own default. Tag Rec.709 (or sRGB) explicitly via Render Queue > Output Module > Color Management (do not leave "Preserve RGB" when a shift occurs).
• The QuickTime gamma bug. QuickTime/AVFoundation apply an extra ~1.96 gamma, so a file can look fine in QuickTime but dark/contrasty in Chrome. Never grade or approve to QuickTime — Chrome, Premiere, or Resolve is the correct reference for web delivery.
• Match preview to final. Toggle "Use Display Color Management" in the comp viewer while reviewing, and verify the export numerically: place a 50% grey (RGB 128) patch, render, re-sample — a value that rises (128 → 150+) confirms a washed-out gamma shift. Confirm the embedded tag with ffprobe (color_primaries/color_transfer/color_space = bt709).

Per-platform export at a glance: ProRes 422 HQ/4444 tagged Rec.709 for editing masters; H.264 (MP4) tagged Rec.709 for web/<video>/social (verify in Chrome); ProRes 4444 + alpha → PNG (sRGB) for transparency; ProRes 4444 / HEVC 10-bit Rec.2020 PQ/HLG for HDR (needs 32 bpc float).

See references/color-management.md for the full diagnosis decision tree, exact menu paths, per-platform export table, the QuickTime workarounds, per-OS/player gamma values, the numeric test-patch method, ffprobe/ffmpeg tag commands, limited-vs-full-range pitfalls, and the pre-export checklist.

Deliver & verify (standalone HTML)

Packaged helper (scripts/): scripts/seek-shot.sh anim.html 0 1.5 3 freezes the ?t=N harness and screenshots each moment; scripts/contact-sheet.sh sheet.png frame-*.png tiles them for one-glance review. See scripts/README.md.

For a web palette/gradient/color-transition deliverable, ship one .html file that opens directly in a browser — no build step. CSS handles the color work; the file is self-contained.

Output contract:

• One .html file: your markup + the gradient/transition in inline <style> (CDN only if a JS interpolation lib is needed).
• One animation driver — a CSS @keyframes drift or a single @property transition; nothing competing.
• Include the freeze harness below so any moment can be screenshotted deterministically.

Freeze harness — pin a CSS-animation frame for screenshots. ?t=N sets a negative animation-delay and pauses, so the gradient/transition lands on the exact frame at N seconds.

<script>
  const t = new URLSearchParams(location.search).get("t");
  if (t !== null) {
    document.querySelectorAll(".bg, .btn").forEach(el => {       // animated elements
      el.style.animationDelay = (-parseFloat(t)) + "s";
      el.style.animationPlayState = "paused";
    });
  }
  window.__ready = true;                                          // ready signal for headless wait
</script>

Verify loop — render → freeze → screenshot → check:

1. Open the file frozen at start / mid / end: …/color.html?t=0, ?t=<period/2>, ?t=<period>.
2. Screenshot each frozen frame.
3. Check fidelity (matches the palette/brief) and color artifacts — at each frozen frame confirm the gradient/transition has no banding and no muddy or gray midpoint (the OKLCH/Lab path stays vivid). Add grain if banding appears.
4. Iterate: if banding or a muddy/gray midpoint shows up, adjust the OKLCH/Lab chroma & lightness (or add grain), re-render the same ?t=N, and re-screenshot to confirm the fix — loop until every frozen frame is clean.

npx playwright screenshot --wait-for-timeout=500 "file://$PWD/color.html?t=8" frame-mid.png

Before you finish:

1. Opens standalone in a browser — no console errors, no missing CDN.
2. One color driver; ?t=N freezes the exact frame correctly.
3. Screenshotted at start / mid / end — no banding, no muddy/gray midpoints, lightness even.
4. prefers-reduced-motion honored (drift paused on a static, readable frame).
5. Interpolation is in OKLCH/Lab (gradients/@property), never raw sRGB.

Quick reference

Need	Do
Palette size	1 primary + 1 accent + 2-3 neutrals
Equal-weight hues	hold L,C in OKLCH, vary H
Vivid gradient	linear-gradient(in oklch, ...)
Smooth color anim	interpolate in OKLCH/Lab, register via @property
Premium bg	stacked radials + grain + 8-20s slow drift
Cinematic grade	teal shadows / orange highlights, subtle
Fix washed-out AE render	tag Rec.709 in Output Module > Color Management; verify in Chrome
Avoid	raw-sRGB interpolation (muddy midpoints); grading to QuickTime

Reference files

• references/palettes-and-interpolation.md — palette construction rules with OKLCH values and named recipes, gradient cookbook (mesh, conic, grain), culori and d3-interpolate code for perceptual interpolation and scales, and the full grading-order checklist with filter/shader examples.
• references/color-management.md — full video/render color management: diagnosis decision tree, AE project/output color settings with exact menu paths, per-platform export table, QuickTime gamma-bug workarounds, per-OS/player gamma values, the numeric test-patch method, ffprobe/ffmpeg tag verification, limited-vs-full-range pitfalls, and the pre-export checklist.