Black and White dithering for the canvas element
First, install the package using npm:
npm install canvas-dither --save
Then, require the package and use it like so:
let Dither = require('canvas-dither'); // Assume we have an existing canvas element with a 2D context // Retrieve the image data of the canvas let image = context.getImageData(0, 0, canvas.width, canvas.height); // Dither the data using the Atkinson algoritm image = Dither.atkinson(image); // Place the image data back on the canvas context.putImageData(image, 0, 0);
This package contains the following algorithms:
A simple threshold which will make all pixels with a luminance over the threshold white and under the threshold black.
Using a Bayer matrix the image is converted to black and white with a cross-hatch pattern.
Altough there is nothing random about this algorithm, the results looks like a random scattering of dots, making especially photos seem very natural.
An improved version of the Floyd-Steinberg algorithm created by Bill Atkinson of MacPaint fame. This algorithm creates less noise in almost white backgrounds compared to Floyd-Steinberg, but has more contrast as a result.