Image Posterize

What is posterization?

Posterization is an effect that reduces the number of distinct colours or tones in an image by quantising each channel to a fixed number of levels. Instead of a smooth gradient from black to white, the image jumps through a series of discrete steps, producing visible colour bands. The name comes from traditional poster printing, which used a limited number of ink colours, and the effect is widely used for its bold, graphic quality in design and illustration.

This tool runs entirely in your browser. When you upload an image, it is decoded through the Canvas API. As you drag the levels slider, the tool reads the raw pixel buffer and, for each red, green and blue channel, rounds the value to the nearest of N evenly spaced levels. A levels value of 2 reduces each channel to just on or off (8 total colours), while higher values progressively preserve more of the original tonal range. The preview updates instantly, and the result can be downloaded as a PNG file.

Posterize vs gradient

Posterization and smooth gradients are opposites. A normal photograph has 256 levels per channel (over 16 million colours), producing gradients that appear continuous to the eye. Posterization deliberately collapses those 256 levels into a smaller set, turning smooth transitions into visible bands. The fewer the levels, the more dramatic the banding. This is sometimes an unwanted artefact of heavy JPEG compression, but as a creative effect it gives images a bold, poster-like, screen-printed quality that is prized in graphic design.

When to use posterize

Posterization is useful whenever you want a bold, graphic look or need to reduce colour complexity. Common use cases include:

How to posterize an image

Posterization is useful whenever you want a bold, graphic look or need to reduce colour complexity. Common use cases include:

• Poster and print design. Create bold, screen-print-style graphics with a limited colour palette.
• Retro and game art. Mimic the look of 8-bit and 16-bit graphics with restricted colour depth.
• Stylised photography. Give photos a dramatic, high-contrast, almost painted appearance.
• Colour simplification. Reduce the number of unique colours before indexing or palette-based export.
• Educational visualisation. Demonstrate how quantisation and colour depth affect image perception.

Whenever you need an image to feel bold, flat and poster-like rather than smooth and photographic, posterization is the right tool.

Colour banding and posterization

Posterizing an image with this tool takes only a few seconds and runs entirely in your browser — no uploads, no sign-up, no watermark. Follow these steps:

1. Upload your image. Click the upload area or drag and drop a JPG, PNG, WebP, GIF or BMP file.
2. Adjust the levels. Drag the slider from 2 to 32. A value of 2 produces the most extreme effect (very few colours), while higher values keep more detail. The preview updates in real time.
3. Download the result. Click "Download Posterized Image" to save the posterized PNG.

Because every step runs locally through JavaScript, your image is never sent to a server. This makes the tool completely private and fast.