pixel-editor/js/_loadImage.js

document.getElementById('open-image-browse-holder').addEventListener('change', function () {
    if (this.files && this.files[0]) {

        //make sure file is allowed filetype
        var fileContentType = this.files[0].type;
        if (fileContentType == 'image/png' || fileContentType == 'image/gif') {

            //load file
            var fileReader = new FileReader();
            fileReader.onload = function(e) {
                var img = new Image();
                img.onload = function() {

                    //create a new pixel with the images dimentions
                    newPixel(this.width, this.height, []);

                    //draw the image onto the canvas
                    currentLayer.context.drawImage(img, 0, 0);

                    var colorPalette = {};
                    var imagePixelData = currentLayer.context.getImageData(0,0,this.width, this.height).data;

                    var imagePixelDataLength = imagePixelData.length;

                    console.log(imagePixelData);
                    for (var i = 0; i < imagePixelDataLength; i += 4) {
                        var color = imagePixelData[i]+','+imagePixelData[i + 1]+','+imagePixelData[i + 2];
                        if (!colorPalette[color]) {
                            colorPalette[color] = {r:imagePixelData[i],g:imagePixelData[i + 1],b:imagePixelData[i + 2]};

                            //don't allow more than 256 colors to be added
                            if (Object.keys(colorPalette).length >= settings.maxColorsOnImportedImage) {
                                alert('The image loaded seems to have more than '+settings.maxColorsOnImportedImage+' colors.');
                                break;
                            }
                        }
                    }

                    //create array out of colors object
                    var colorPaletteArray = [];
                    for (var color in colorPalette) {
                        if( colorPalette.hasOwnProperty(color) ) {
                            colorPaletteArray.push('#'+rgbToHex(colorPalette[color]));
                        }
                    }
                    console.log('COLOR PALETTE ARRAY', colorPaletteArray);

                    //create palette form colors array
                    createColorPalette(colorPaletteArray, false);

                    //track google event
                    ga('send', 'event', 'Pixel Editor Load', colorPalette.length, this.width+'/'+this.height); /*global ga*/

                };
                img.src = e.target.result;
            };
            fileReader.readAsDataURL(this.files[0]);
        }
        else alert('Only PNG and GIF files are allowed at this time.');
    }
});