Gradient Map shader preview: Recolour an image, or any layer stack, through your gradient.
ittybitty

Gradient Map

Recolour an image, or any layer stack, through your gradient.

Code

The usage always matches the preview, layers and performance settings included. No build step or package.

Copy embed gives one block to paste into any page or site builder, no setup. For your own code: add gradient-map.js, ittybitty-shader.js, runtime.js, texture.js next to this page. Highlighted values follow the controls.

<!-- Quickest: one element. Size it with CSS; it fills its box. -->
<script type="module" src="./ittybitty-shader.js"></script>
<ittybitty-shader effect="gradient-map" style="width: 100%; aspect-ratio: 16 / 10;"></ittybitty-shader>

<!-- Or with JavaScript, for full control: -->
<canvas id="gradient-map" aria-hidden="true" style="width: 100%; aspect-ratio: 16 / 10; display: block"></canvas>

<script type="module">
  import { gradientMap } from './gradient-map.js';

  const canvas = document.getElementById('gradient-map');
  const effect = gradientMap(canvas, {
    image: '/examples/still-life.webp',
    style: 'smooth',
    steps: 5,
    contrast: 1.1,
    brightness: 0,
    reverse: false,
    palette: [[0, '#1a1036'], [0.45, '#d4336f'], [0.8, '#ffb86b'], [1, '#fff6e0']],
    // Performance
    dpr: 2,
    adaptive: true,
  });

  // Later: effect.set(…), effect.pause(), effect.resume(), effect.destroy()
</script>

Details

The classic gradient map: lightness from shadow to highlight replaced by your gradient, smoothly or in flat posterised steps. On its own it maps an image; as a layer it recolours everything beneath it, so any effect can take any palette. It draws once per change.

Payload
5.1 KB brotli for gradient-map.js and ittybitty-shader.js and runtime.js and texture.js, measured at build time. See the method.
Resolution
Device pixel ratio capped at 2.
Frame rate
None. One frame per change.
When unseen
Stops rendering when the canvas leaves the viewport or the tab is hidden, and resumes where it left off.
Reduced motion
Nothing to change: it never moves.
Layers
Up to five effects fuse into one shader and one draw call. Filters such as dithering and halftone process the layers beneath them.
Browsers
Any browser with WebGL2: Chrome and Edge 56+, Firefox 51+, Safari 15+.
Licence
MIT. Copy it, change it, ship it.