Image Posterize
Quantises each RGB channel independently into a chosen number of evenly-spaced levels — 2 levels gives a screen-print look, 8 a vintage photo print, 16 a barely-noticeable smoothing. Floyd-Steinberg error diffusion is optional: leave it off for hard flat banding, turn it on for retro-game style stippling that hides the banding. Unlocking per-channel levels lets you produce duotone-style effects (e.g., 2 red levels, 8 green, 2 blue).
How to use
- Drop or pick an image.
- Slide Levels down — 4 is a good starting point for the poster look.
- Toggle dithering on if the bands look too harsh.
- Unlock channels for asymmetric, duotone-style results.
Frequently asked questions
- What's the difference vs the Image Pixelate tool?
- Pixelate reduces spatial resolution (chunky pixels), Posterize reduces tonal resolution (fewer distinct shades). You can stack them — pixelate first, then posterize — for a true low-bit look.
- Why does dithering make my file bigger?
- PNG compression works by finding runs of identical bytes. Dithering breaks those runs into pseudo-random noise, which compresses much worse. For the smallest file, leave dithering off; for the best perceived quality at low levels, leave it on.
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