image-filter-core

Small library that relies on webworkers to apply image transformations.

There are several modules that use image-filter-core, such as:

• image-filters
• image-filter-brightness
• image-filter-contrast
• image-filter-grayscale
• image-filter-threshold
• image-filter-sepia
• image-filter-invert
• image-filter-gamma
• image-filter-colorize

But you can easily create your own transformation function and rely on image-filter-core to handle the webworkers and to split the work.

Install

npm install image-filter-core --save

Methods

# getCanvas()

It returns a canvas with the given width and height

var imageFilterCore = require('image-filter-core');
var canvas = imageFilterCore.getCanvas(100, 100);

# convertImageDataToCanvasURL()

Given a ImageData it returns the dataURL

var imageFilterCore = require('image-filter-core');
var canvasURL = imageFilterCore.convertImageDataToCanvasURL(imageData);

# apply()

Provide the ImageData, the transformation function, the options to be passed to the transformation function and the number of workers to split the work.

var imageFilterCore = require('image-filter-core');
 
imageFilterCore.apply(data, transform, options, nWorkers)
    .then(function (imageData) {
        // Do whatever you want with imageData
    });

The transform function receives ImageData, the length of data to transform and the options that the developer provided to image-fiter-core, example transformation function for the threshold effect:

function transform (data, length, options) {
    for (var i = 0; i < length; i += 4) {
        var r = data[i];
        var g = data[i + 1];
        var b = data[i + 2];
        var v = (0.2126 * r + 0.7152 * g + 0.0722 * b >= options.threshold) ? 255 : 0;
        data[i] = data[i + 1] = data[i + 2] = v;
    }
}