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 () {
    $("input[type=file]").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");
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Published in: Javascript

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Web Geek, Google Developer Expert
Amit Agarwal

Amit Agarwal is a Google Developer Expert in Google Workspace and Google Apps Script. He holds an engineering degree in Computer Science (I.I.T.) and is the first professional blogger in India. He is the developer of Mail Merge for Gmail and Document Studio. Read more on Lifehacker and YourStory

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