ColorQuantize

ColorQuantize[image] gives an approximation to image by quantizing to distinct colors.

ColorQuantize[image, n] uses at most n distinct colors.

ColorQuantize[image, {col1, ..., coln}] represents an image using only the specified colors.

Examples

Quantize to 8 colors:

ColorQuantize[img, 8]

Quantize to specific palette:

ColorQuantize[img, {Red, Green, Blue, White, Black}]

Please visit the official Wolfram Language Reference for more details.