Imagemagick

From Habitat: Giardino

Imagemagick

Tricks

Gray Scale

 magick convert -set colorspace Gray -separate -average /path/to/my/file.jpeg  export.jpeg

Monochrome

Return bitmap

magick convert -monochrome /path/to/my/file.jpeg  export.png

Colors

The number of colours can be changed

magick convert /path/to/my/file.jpeg -dither FloydSteinberg -colors 3 export.png

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magick convert /path/to/my/file.jpeg -colors 3 -colorspace gray -normalize

renders:

3 colors normalization