Detects whether an image is predominantly dark or light by sampling pixels via OffscreenCanvas. Uses APCA perceptual lightness (sRGB linearization + power curve) for accurate detection, especially on saturated colors. Runs entirely off the paint path: no visible canvas, no layout thrash. Supports regional sampling for detecting luminance where text overlays will appear. Returns null while loading and falls back gracefully on CORS or network errors.
pnpm dlx shadcn@latest add "https://astryx.atmeta.com/shadcn/hook-use-image-mode.json"