Floyd-Steinberg and Burkes dithering implementations in Racket
I wrote these functions to print images to a thermal receipt printer, which has only black and white pixels.
Exported functions are:
bitmap->floyd-steinberg
bitmap->burkes
Each accepts an alpha-red-green-blue argb bitmap and produces and returns a dithered bitmap also in argb format, but with each pixel either pure white or pure black.
These exprs are demo/test code (e.g. type them into REPL):
(require net/url)
(define flowers
(read-bitmap
(get-pure-port
(string->url "https://www.almanac.com/sites/default/files/birth_month_flowers-primary-1920x1280px_pixabay.jpg"))
#:backing-scale 3.))
flowers
(bitmap->floyd-steinberg flowers)
(bitmap->burkes flowers)
