Convert Image to Base64 Data URI

Published in: JavaScript

In Spreadsheet Paintings, you upload a photograph from the local disk and it transforms the picture into pixel art. Internally, the JavaScript resizes the image using the HTML5 Canvas API and then uploads the base64-encoded representation of the canvas data to the Google Script using the HTMLService where the pixels are converted into RGB colors.

<input type="file" id="image">
    $("document").ready(function() {
            .on('change', function(f) {
                var file =[0];
                if (file) {
                    var reader = new FileReader();
                    var image = new Image();
                    reader.onload = function(e) {
                        image.src =;
                        var canvas = $('canvas')[0];
                        canvas.height = image.height;
                        canvas.width = image.width;
                        var ctx = canvas.getContext('2d');
                        ctx.drawImage(image, 0, 0);
                        var dataURL = canvas.toDataURL('image/png');
Published in: JavaScript

Looking for something? Find here!

Meet the Author

Web Geek, Tech Columnist
Amit Agarwal

Amit Agarwal is a Google Developer Expert in GSuite and Google Apps Script. He holds an engineering degree in Computer Science (I.I.T.) and is the first professional blogger in India. Read more on Lifehacker and YourStory

Get in touch