Free web tool
Reduce color levels to create a posterized image effect.
Reduce the number of tonal levels in each RGB channel to create deliberately larger color steps. It is useful for quickly comparing how a photo changes as it moves toward a poster-like or illustrated look.
The setting applies separately to red, green, and blue. With 6 levels per channel, the theoretical RGB palette can still contain up to 6 × 6 × 6 = 216 combinations.
So if you expected “six colors total,” the result can look much more colorful than expected. Try 4, 3, then 2 levels when you want a stronger posterized effect.
Only the RGB channels are posterized. The Alpha channel is left unchanged, so a transparent PNG keeps its transparent regions.
If you want to verify the transparency numerically, use Image transparency / Alpha checker to inspect fully transparent, semi-transparent, and opaque pixels.
Posterization reduces tonal steps while keeping color. If the goal is an explicit black-and-white result, Image threshold / binarizer is easier to control because it splits pixels by luminance.
Choose posterize when you want to keep color character; choose thresholding when shape and black/white separation matter more.
Posterization creates hard color boundaries. Re-encoding immediately as JPEG can introduce compression artifacts around those boundaries.
This tool therefore exports PNG. If your final workflow needs JPEG or WebP, review the PNG first and then use Image format converter.