Afterimage shader preview: Turns a photo into a long-exposure dream: smeared, ghosted, cooled, burning and grainy.
ittybitty

Afterimage

Turns a photo into a long-exposure dream: smeared, ghosted, cooled, burning and grainy.

Code

Use as

Copy embed: paste into Webflow, Framer, Squarespace or any HTML · Copy for agent: paste into Cursor or Claude · Copy code: the files for your own build.

For your own build, add afterimage.js, ittybitty-shader.js, runtime.js, pointer.js and 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="afterimage" style="width: 100%; aspect-ratio: 16 / 10;"></ittybitty-shader>

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

<script type="module">
  import { afterimage } from './afterimage.js';

  const canvas = document.getElementById('afterimage');
  const effect = afterimage(canvas, {
    showGrain: true,
    showFringe: true,
    showLeak: false,
    image: '/examples/night-city.webp',
    mode: 'pan',
    smear: 0.6,
    angle: 6,
    softness: 0.55,
    smudge: 0.5,
    ghost: 0.45,
    glow: 0.7,
    heat: 1,
    grain: 0.6,
    fringe: 0.5,
    leak: 0.6,
    fade: 0.55,
    speed: 0.4,
    palette: [[0, '#1b1a50'], [0.36, '#2e4fa6'], [0.7, '#4f9ac6'], [1, '#c2e8de']],
    hot: '#ff4a26',
    interactive: true,
    // Performance
    dpr: 1,
    adaptive: true,
  });

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

Details

The frame is dragged along a pan, a handheld shake, a zoom or a swirl, lights trailing furthest, then smudged and doubled into a second exposure. Everything is washed into your cool tones while warm lights burn toward the hot colour, a halo spills around anything bright, edges split into colour, the corners fall into shadow and moving film grain covers the lot. Silhouettes survive as soft shapes, so people and cars still read. The pointer drags the picture where it passes.

Payload
9.2 KB brotli for afterimage.js, ittybitty-shader.js, runtime.js, pointer.js and texture.js, measured at build time.
Resolution
Pixel ratio 1: it is all blur and grain.
Frame rate
Display rate.
When unseen
Stops rendering when the canvas leaves the viewport or the tab is hidden, and resumes where it left off.
Reduced motion
Shows a single still frame. Controls still update it.
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.
Source
afterimage.js on GitHub, in a public repo that logs every change.