Dithering
Dithering places two colours in a pattern so that, from a distance, the eye blends them into something in between. Used with care it adds texture and soft transitions.
What it is
When a palette has only a few colours, you cannot draw a smooth gradient. Dithering fakes one: you mix two neighbouring colours in a pattern, and the eye averages them. A checkerboard of dark and mid blue reads, from a step back, as a blue halfway between.
The most common patterns are:
- Checkerboard: alternating pixels, the 50 % mix.
- Ordered (Bayer) patterns: a fixed grid of steps (25 %, 50 %, 75 %) that gives tidy, regular transitions.
- Noise patterns: irregular, like blue noise, which avoid visible grids but look grainier.
Why artists do it
On old hardware with tiny palettes, dithering was the only way to get more apparent colours. Today it is a style choice. It gives texture to stone, fur and sand, softens the edge between two light bands on a large surface, and gives a retro feel.
Common mistakes
- Dithering everything. On small sprites a pattern turns into noise. A 32 pixel character rarely needs it.
- Dithering between colours that are too far apart. Black and white in a checkerboard does not read as grey; it reads as a pattern. Dither between neighbours in a ramp.
- Patterns that crawl. In animation, a pattern fixed to the screen shimmers as the shape moves under it. This is one of the main reasons artists avoid dithering on characters.
- Mixing pattern scales. A 2×2 pattern next to a 1×1 pattern looks like two pixel sizes, a kind of mixel.
How to do it by hand
- Shade the area with flat bands first.
- Choose the boundary you want to soften.
- Along that boundary, add a strip of checkerboard one or two pixels wide. For a wider fade, use a sparse pattern (one pixel in four), then checkerboard, then the reverse sparse pattern.
- Zoom out to 1× and check it reads as a blend, not as a texture you did not mean.
- In animation, move the pattern with the surface, not with the canvas.
How Pixor does it
Pixor can dither between light bands with an ordered (Bayer) or a blue-noise pattern, from none to strong. The pattern is held on the surface of the model, so it moves with the shape rather than shimmering across it as the model animates or turns. Dithering is one node of the Style graph, so you can turn it off for characters and on for scenery.
Related
- Palette ramps: pick neighbours to dither between
- Sub-pixel animation
- Looks, Palettes and the settings manual
Questions
Should I use dithering in my sprites?
Only if it suits the style. Many modern games use little or none on characters. It works best on large, slow surfaces like skies, rock and cloth.
Why does my dithering shimmer when the sprite moves?
The pattern is fixed to the screen instead of the surface. As the shape moves, pixels switch colour every frame. Keep the pattern attached to the surface.
What is ordered or Bayer dithering?
A regular pattern from a small threshold grid. It gives tidy checkerboards and steps, which suit pixel art better than random noise.