Dither - Color Quantization and Dithering

This is a small program dedicated to reducing the number of colors in an image. It operates with files in binary PPM format (Portable PixMap), and features automatic palette generation (using a median-cut algorithm) and dithering implemented with the Floyd-Steinberg method.

Installing

On macOS with Homebrew

$ brew install tessarin/core/dither

Manual Installation

Running make will compile the program and generate the documentation (requires Perl). To install, move the executable and manual file to the appropriate directories.

$ make
$ mv dither ~/bin
$ mv dither.1 ~/man/man1

Individual targets can also be specified for only compiling or generating the manual page:

$ make dither
$ make doc

Usage

$ dither [-p name.size] [-dv] input output

Detailed information about the program options are included in the manual.

Features

By default, dither will use a 3-bit RGB palette and dithering when processing an image. Other possible palettes include:

• Grayscale of any given size
• Automatic, generated with the given size using the median-cut quantization algorithm
• Custom palette

Dithering on the final image can be disabled and the program also can be used to just generate a palette.