Instant screen-print aesthetic
Reducing levels mimics lithography and silkscreen, where each extra ink pass costs money — the look is graphic, deliberate and eye-catching.
ImageRuns in your browser
Posterize Image
Crush smooth gradients into bold flat colour bands for a retro poster look.
- Upload
- Single file · 25 MB max
- Privacy
- Nothing is uploaded
- Cost
- Free · no sign-up · no watermark
Loading tool…
The tool is loading its code on your device. This happens once and is cached for later visits.
Processed entirely on your device
Your file is read, transformed and re-encoded inside this browser tab using JavaScript. There is no upload endpoint — nothing leaves your machine, nothing is stored, and the result is created as a local object URL that disappears when you close the page.
Overview
About the Posterize Image
Posterize an image free online by reducing it to a chosen number of colour levels, creating bold flat bands and a screen-printed retro style in your browser.
How posterization quantises colour
A normal image uses up to 256 shades per channel. Posterization divides that range into N steps and snaps every pixel to the nearest step, so smooth gradients collapse into flat bands. The fewer the steps, the bolder and more graphic the result.
The screen-print heritage
Silkscreen and litho printing lay a limited number of inks, each as a flat area of colour. Posterizing digitally reproduces that constraint, which is why the effect reads as vintage protest posters, album covers and comic art rather than as a photo filter.
Picking levels and pairing effects
Start at 4-6 levels for a balanced pop-art look. Combining posterize with a saturation boost makes the bands sing, while a contrast lift first sharpens the boundaries between them. For pure two-tone work use the black-and-white threshold tool instead.
Runs entirely on your device
The quantisation loop touches each pixel once on an in-browser canvas and exports a lossless PNG, keeping band edges pixel-crisp and your source file private.
Step by step
How to use the Posterize Image
Drop an image onto the upload area or browse your device.
Set the colour-levels slider; fewer levels means bolder bands.
Preview the banding on gradients like sky and skin.
Download the posterized PNG for print or graphic use.
Why use it
Benefits and common use cases
What this tool is good for, and what it deliberately does not try to do.
Simplifies busy photos
Flat bands strip micro-detail, turning a cluttered photo into a readable graphic suitable for posters, avatars and thumbnails.
Local pixel-accurate pass
The level quantisation runs per channel on a local canvas, so band edges are crisp and the file never leaves your browser.
Questions
Frequently asked questions
Short, honest answers about quality, limits and privacy.
How many levels should I choose?
2-3 levels gives an extreme, near-duotone graphic. 4-6 reads as classic pop-art poster. 8+ keeps most of the photo recognisable while still stylised. Preview at full size before downloading.
Is posterize the same as black and white threshold?
No. Threshold keeps two values total; posterize keeps N levels per colour channel, so colour survives in flat bands rather than collapsing to black and white.
Why do I see harsh edges on smooth skies?
That banding is the effect itself: a continuous gradient is snapped to the nearest level. Fewer levels make wider, more obvious bands — which is usually the point.