canvas-dither

Black and White dithering for the canvas element

Usage

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:

Threshold

A simple threshold which will make all pixels with a luminance over the threshold white and under the threshold black.

Dither.threshold(imageData, threshold);

Bayer

Using a Bayer matrix the image is converted to black and white with a cross-hatch pattern.

Dither.bayer(imageData, threshold);

Floyd-Steinberg

Altough there is nothing random about this algorithm, the results looks like a random scattering of dots, making especially photos seem very natural.

Dither.floydsteinberg(imageData);

Bill Atikinson

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.

Dither.atkinson(imageData);

License

MIT