Online Batch Image Posterize Tool
Batch process multiple images: reduce the levels of each color channel. Processing takes place locally in your browser.
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What this tool actually does
The page loads up to 30 browser-decodable images by multiple selection or drag and drop. A file may be at most 25 MB and 24,000,000 decoded pixels; the complete batch is capped at 100 MB and 40,000,000 decoded pixels.
Checkable behavior
Color levels is the only effect setting, with a displayed range of 2 to 32 and a default of 6. The same setting is applied to every loaded image when Generate image is pressed.
Controls, output and limitations
Each red, green and blue byte is independently rounded to the nearest value on a uniform grid whose step is 255 divided by levels minus one. With 6 levels, the possible channel values are 0, 51, 102, 153, 204 and 255; RGB(120, 180, 245) becomes RGB(102, 204, 255). Alpha is retained.
Lower level counts create flatter poster-like bands; higher counts retain more tonal steps. This is per-channel RGB quantization, not palette optimization, dithering, vector tracing or print color separation.
Results keep the original pixel dimensions and are downloaded as separate PNG files named with -posterize.png. There is no ZIP or output-format selector, and metadata and animation are not preserved. Processing remains in the current browser.
Enter an integer from 2 to 32 in the numeric field (default 6). Empty, fractional or out-of-range values are rejected and invalidate the previous download. Levels apply separately to R, G and B: 2 levels can yield up to 8 opaque RGB colors, not just black and white. Every run starts from the loaded source; 0 is not a reset option and 32 still quantizes colors.
Per image: ≤25 MiB and ≤24,000,000 pixels. Per batch: ≤100 MiB and ≤40,000,000 pixels. Selecting over 30 files or any invalid image rejects the whole batch.
Processing takes place locally in your browser.