DitherForge — Dithered Gradients for Aseprite

Hand-placing dither dots is meditative for about ninety seconds. Then it is just work.

DitherForge fills your selection with an ordered-dither gradient between any two colours — and because it is ordered dithering rather than error diffusion, it tiles cleanly, stays deterministic, and never smears when you edit next to it.

Controls that matter

• 4 directions — horizontal, vertical, diagonal, radial
• 3 Bayer patterns — 2×2 chunky, 4×4 the classic, 8×8 fine
• 2–16 bands — 2 gives the classic two-colour dither; raise it to quantise a smooth ramp into a clean, limited set of shades
• Bias — slide the midpoint without changing the endpoints or direction
• Honours your selection, including non-rectangular ones — the marquee is the shape, not just a bounding box
• Outputs to a new layer by default, so nothing you already drew is at risk. One undo.

Tested against real Aseprite

The maths core has a headless suite covering every Bayer matrix (each verified to be a full rank permutation), threshold bounds, all four ramp directions, monotonicity under bias, band quantisation, and the degenerate cases — 1-pixel-wide regions, single-step ramps. An end-to-end test then runs real Aseprite and asserts the produced gradient is genuinely a gradient: pure at both ends, dithered in the middle, monotonically increasing across the region, and correctly clipped to a selection.

Install

Double-click the .aseprite-extension file, or Edit → Preferences → Extensions → Add. Requires Aseprite 1.3+.

Transparency: DitherForge’s code is AI-assisted, disclosed via itch’s AI tagging. It generates no imagery — it places dots between two colours you picked.