What 1-Bit Dither Does
You have an image with 16 million colors. You're going to express it using two: black and white. Dithering decides where each one goes.
The illusion of gray comes from dot density. Lots of black pixels close together = looks dark. Sparse black on white = looks light. Stand back from the screen — your eye averages it.
Four Algorithms
Each produces a distinct look. Try all of them on the same image.
Threshold
Pixels above the threshold become white, below become black. No mixing. Hard, posterized. Best for high-contrast graphics and logos.
Floyd–Steinberg
Error diffusion: when a pixel rounds to black or white, the leftover "error" is pushed to neighboring pixels. Result: soft, slightly fuzzy gradients. The most photographic of the four.
Atkinson
Like Floyd–Steinberg but only diffuses 75% of the error and skips some neighbors. The result is brighter and more contrasty — this is the dither used on the original Macintosh.
Bayer
Uses an ordered matrix (2×2, 4×4, or 8×8) to decide threshold per pixel. The output has a visible regular pattern — looks like a pre-print halftone. Best when you want the pattern visible.
Parameters
Threshold (0–255)
Center point for black vs white. 128 = neutral.
Bayer Size (2 / 4 / 8) — Bayer only
Smaller = chunkier visible pattern. Larger = finer, almost smooth.
Pixel Scale (1–8)
Downsamples before dithering. Higher = bigger, retro lo-fi dots.
Good Subjects
Recipes
Original Macintosh
Newspaper Halftone
Risograph
Fax Machine
What to Avoid
Combinations
The Idea
Two colors is more than enough. The rest is math.