Real-time chrominance vectorscope for Adobe Photoshop and Lightroom Classic. Analyze color distribution, overlay harmony zones, and visualize density -- all inside your editing workflow.
Website · Download · Documentation
Chromascope maps every pixel in your image onto a circular vectorscope plot, showing where your colors live in chrominance space. Use it to:
- Spot color casts and imbalances at a glance
- Check skin tones against the industry-standard reference line
- Overlay harmony zones (complementary, triadic, analogous, etc.) and rotate them to find the right grade
- Toggle scatter and bloom density modes for different levels of detail
Works as a native panel in Photoshop (UXP) and as a floating dialog in Lightroom Classic, updating in real time as you adjust develop sliders.
Three visualization modes show chrominance distribution at different levels of detail:
Scatter · individual pixel dots Heatmap · density-colored frequency map Bloom · radial glow with additive blending
Overlay color harmony zones on the vectorscope to guide your grading decisions. Rotate the zones interactively to find the best fit for your image.
git clone https://github.com/kevinkiklee/chromascope.git
cd chromascope
./scripts/setup.shThis installs dependencies, builds all packages, compiles the Rust binary, and runs tests. See docs/SETUP.md for prerequisites and manual setup.
npx turbo dev # Start all dev servers
cd packages/core && npm run dev # Core library only (Vite)npm run build:pluginsBuilds the core library, compiles the Rust processor for all platforms, assembles the Photoshop and Lightroom plugins.
The core library bundles to a single HTML file that runs inside the UXP panel WebView. The plugin reads pixel data via the Imaging API and sends it to the core for rendering. Edits flow back through a typed message protocol.
Photoshop --PixelsMessage--> Core WebView (vectorscope)
Photoshop <--EditMessage--- Core WebView (color correction)
Lightroom's Lua SDK can't embed WebViews or access pixel data directly. Instead, the Rust processor binary handles everything outside Lua's reach:
LrC plugin
1. requestJpegThumbnail --> JPEG from catalog
2. processor pipeline --> decode + render in one shot → vectorscope JPEG
3. f:picture --> display in dialog
Two change-detection paths keep the scope in sync:
- Poll loop (150ms) — hashes the full
getDevelopSettings()table with a recursive djb2 fingerprint. Detects changes in any develop panel (Basic, HSL, Masking, Calibration, Detail, Lens Corrections, Transform, Effects, and more). - Adjustment observer — throttled renders during slider drag (~200ms cadence) with a correction render after settle, giving ~2-3 fps live feedback.
A busy-guard with coalescing prevents overlapping renders, and frame alternation between two output files forces Lightroom to release cached images (preventing memory leaks).
The processor CLI has three subcommands:
| Command | Purpose |
|---|---|
processor pipeline |
Decode JPEG/TIFF + render vectorscope in one shot (primary command) |
processor decode |
Decode JPEG/TIFF to raw RGB, resized to target dimensions |
processor render |
Render a vectorscope JPEG from raw RGB data |
pipeline combines decode and render into a single process, saving ~50-100ms of spawn overhead vs. running them separately. --save-rgb writes the decoded pixels for overlay-only re-renders.
Render options: --density (scatter, heatmap, bloom), --scheme (complementary, splitComplementary, triadic, tetradic, analogous), --rotation, --overlay-color (white, yellow, cyan, green, magenta, orange), --hide-skin-tone, --color-space (hsl, ycbcr, cieluv), --output-format (jpeg, png).
packages/core/ TypeScript vectorscope engine (math, rendering, UI)
packages/processor/ Rust CLI (image decode + vectorscope render)
plugins/photoshop/ Photoshop UXP panel plugin
plugins/lightroom/ Lightroom Classic plugin (Lua + Rust binary)
web/ Static marketing site + documentation
scripts/ Build and setup automation
| Monorepo | Turborepo |
| Core | TypeScript, Vite 6, Vitest, Canvas 2D |
| Processor | Rust, image crate, clap |
| Photoshop | Adobe UXP, batchPlay, Imaging API |
| Lightroom | Lua, LrDevelopController, LrTasks |
| Web | Static HTML, Tailwind CSS v4 (built) |
packages/core -----> plugins/photoshop (embeds built HTML)
+--> plugins/lightroom (embeds built HTML)
packages/processor -> plugins/lightroom (binary copied to bin/<platform>/)
web (independent)
See docs/CONTRIBUTING.md for development workflow, commit conventions, and architecture notes.
MIT. See LICENSE for details.