Reading a PNG image in Node.js

This one does both PNG decoding and encoding without native dependancies:

pngjs - PNG encoder/decoder for Node.js with no native dependencies.

An example for inverting the colors of a PNG:

var fs = require('fs'),PNG = require('pngjs').PNG;fs.createReadStream('in.png')  .pipe(new PNG())  .on('parsed', function() {    for (var y = 0; y < this.height; y++) {        for (var x = 0; x < this.width; x++) {            var idx = (this.width * y + x) << 2;            // invert color            this.data[idx] = 255 - this.data[idx]; // R            this.data[idx+1] = 255 - this.data[idx+1]; // G            this.data[idx+2] = 255 - this.data[idx+2]; // B            // and reduce opacity            this.data[idx+3] = this.data[idx+3] >> 1;        }    }    this.pack().pipe(fs.createWriteStream('out.png'));});

I was about to became mad searching, but I found one:

png.js ― A PNG decoder in JS for the canvas element or Node.js.

var PNG = require('png-js');var myimage = new PNG('myimage.png');var width  = myimage.width;var height = myimage.height;myimage.decode(function (pixels) {    //Pixels is a 1D array containing pixel data});

Please note it's pure JavaScript. Works both in the browser <canvas> and in Node.JS.

There are more properties apart from width and height, see this source.

I think

var myimage = new PNG('myimage.png');

should be

var myimage = new PNG.load('myimage.png');