Web/API/HTMLCanvasElement/toDataURL

The HTMLCanvasElement.toDataURL() method returns a data URI containing a representation of the image in the format specified by the type parameter (defaults to PNG). The returned image is in a resolution of 96 dpi.

If the height or width of the canvas is 0 or larger than the maximum canvas size, the string "data:," is returned.
If the requested type is not image/png, but the returned value starts with data:image/png, then the requested type is not supported.
Chrome also supports the image/webp type.

Syntax

canvas.toDataURL(type, encoderOptions);

Parameters

type Optional: A DOMString indicating the image format. The default format type is image/png.
encoderOptions Optional: A Number between 0 and 1 indicating the image quality to use for image formats that use lossy compression such as image/jpeg and image/webp. If this argument is anything else, the default value for image quality is used. The default value is 0.92. Other arguments are ignored.

Return value

A DOMString containing the requested data URI.

Exceptions

SecurityError: The canvas's bitmap is not origin clean; at least some of its contents have or may have been loaded from a site other than the one from which the document itself was loaded.

Examples

Given this <canvas> element:

<canvas id="canvas" width="5" height="5"></canvas>

You can get a data-URL of the canvas with the following lines:

var canvas = document.getElementById('canvas');
var dataURL = canvas.toDataURL();
console.log(dataURL);
// "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNby
// blAAAADElEQVQImWNgoBMAAABpAAFEI8ARAAAAAElFTkSuQmCC"

Setting image quality with jpegs

var fullQuality = canvas.toDataURL('image/jpeg', 1.0);
// data:image/jpeg;base64,/9j/4AAQSkZJRgABAQ...9oADAMBAAIRAxEAPwD/AD/6AP/Z"
var mediumQuality = canvas.toDataURL('image/jpeg', 0.5);
var lowQuality = canvas.toDataURL('image/jpeg', 0.1);

Example: Dynamically change images

You can use this technique in coordination with mouse events in order to dynamically change images (gray-scale vs. color in this example):

HTML

<img class="grayscale" src="myPicture.png" alt="Description of my picture" />

JavaScript

window.addEventListener('load', removeColors);

function showColorImg() {
  this.style.display = 'none';
  this.nextSibling.style.display = 'inline';
}

function showGrayImg() {
  this.previousSibling.style.display = 'inline';
  this.style.display = 'none';
}

function removeColors() {
  var aImages = document.getElementsByClassName('grayscale'),
      nImgsLen = aImages.length,
      oCanvas = document.createElement('canvas'),
      oCtx = oCanvas.getContext('2d');
  for (var nWidth, nHeight, oImgData, oGrayImg, nPixel, aPix, nPixLen, nImgId = 0; nImgId < nImgsLen; nImgId++) {
    oColorImg = aImages[nImgId];
    nWidth = oColorImg.offsetWidth;
    nHeight = oColorImg.offsetHeight;
    oCanvas.width = nWidth;
    oCanvas.height = nHeight;
    oCtx.drawImage(oColorImg, 0, 0);
    oImgData = oCtx.getImageData(0, 0, nWidth, nHeight);
    aPix = oImgData.data;
    nPixLen = aPix.length;
    for (nPixel = 0; nPixel < nPixLen; nPixel += 4) {
      aPix[nPixel + 2] = aPix[nPixel + 1] = aPix[nPixel] = (aPix[nPixel] + aPix[nPixel + 1] + aPix[nPixel + 2]) / 3;
    }
    oCtx.putImageData(oImgData, 0, 0);
    oGrayImg = new Image();
    oGrayImg.src = oCanvas.toDataURL();
    oGrayImg.onmouseover = showColorImg;
    oColorImg.onmouseout = showGrayImg;
    oCtx.clearRect(0, 0, nWidth, nHeight);
    oColorImg.style.display = "none";
    oColorImg.parentNode.insertBefore(oGrayImg, oColorImg);
  }
}

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'HTMLCanvasElement.toDataURL' in that specification.	Living Standard	No change since the latest snapshot, HTML5
HTML 5.1The definition of 'HTMLCanvasElement.toDataURL' in that specification.	Recommendation
HTML5The definition of 'HTMLCanvasElement.toDataURL' in that specification.	Recommendation	Snapshot of the HTML Living Standard containing the initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`toDataURL`	Chrome Full support 1	Edge Full support 12	Firefox Full support 2	IE Full support 9	Opera Full support 9	Safari Full support 4	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3.2	Samsung Internet Android Full support 1.0

Legend

Full support: Full support