This is a small utility that reduces the color palette of an image so that it is suitable for an e-ink display. It uses Floyd-Steinberg dithering to produce adequate results.

It supports all of the image format offered by the image crate. The output format is automatically determined by the extension of the output filename.

It is a small, portable, and self-contained application similar to Waveshare's Convertertocolor. The only requirements are Rust and Cargo.

Six color palettes are available:

Palette	Alias	Description
six-color	6	Spectra E6 palette (this is the default)
black-white	bw	Black and white
black-white-red	bwr	Black, white, and red
black-white-yellow	bwy	Black, white, and yellow
four-color	4	Black, white, red, and yellow
n-color	n	Black, white, blue, green, orange, red, yellow

Example:

    $ cargo run -p bw input.png output.bmp

The resulting images have been tested on Waveshare's 4" e-Paper HAT+ (E).