ImageCapture

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The ImageCapture interface of the MediaStream Image Capture API provides an interface for capturing images from a photographic device referenced through a valid MediaStreamTrack.

Constructor

ImageCapture.ImageCapture()
Creates a new ImageCapture object.

Properties

ImageCapture.track Read only
Returns a reference to the MediaStreamTrack passed to the constructor.

Methods

ImageCapture.takePhoto()
Takes a single exposure using the video capture device sourcing a MediaStreamTrack and returns a Promise that resolves with a Blob containing the data.
ImageCapture.getPhotoCapabilities()
Returns a Promise that resolves with a PhotoCapabilities object containing the ranges of available configuration options. 
ImageCapture.getPhotoSettings()
Returns a Promise that resolves with a PhotoSettings object containing the current photo configuration settings.
ImageCapture.grabFrame()
Takes a snapshot of the live video in a MediaStreamTrack, returning an ImageBitmap, if successful.

Example

The following code is taken from Chrome's Grab Frame - Take Photo Sample. Since ImageCapture requires some place to capture an image from, the example below starts with a device's media device (in other words a camera). This example shows, roughly, a MediaStreamTrack extracted from a device's MediaStream. The track is then used to create an ImageCapture object so that takePhoto() and grabFrame() can be called. Finally, it shows how to apply the results of these calls to a canvas object.

var imageCapture;

function onGetUserMediaButtonClick() {
  navigator.mediaDevices.getUserMedia({video: true})
  .then(mediaStream => {
    document.querySelector('video').srcObject = mediaStream;

    const track = mediaStream.getVideoTracks()[0];
    imageCapture = new ImageCapture(track);
  })
  .catch(error => console.log(error));
}

function onGrabFrameButtonClick() {
  imageCapture.grabFrame()
  .then(imageBitmap => {
    const canvas = document.querySelector('#grabFrameCanvas');
    drawCanvas(canvas, imageBitmap);
  })
  .catch(error => console.log(error));
}

function onTakePhotoButtonClick() {
  imageCapture.takePhoto()
  .then(blob => createImageBitmap(blob))
  .then(imageBitmap => {
    const canvas = document.querySelector('#takePhotoCanvas');
    drawCanvas(canvas, imageBitmap);
  })
  .catch(error => console.log(error));
}

/* Utils */

function drawCanvas(canvas, img) {
  canvas.width = getComputedStyle(canvas).width.split('px')[0];
  canvas.height = getComputedStyle(canvas).height.split('px')[0];
  let ratio  = Math.min(canvas.width / img.width, canvas.height / img.height);
  let x = (canvas.width - img.width * ratio) / 2;
  let y = (canvas.height - img.height * ratio) / 2;
  canvas.getContext('2d').clearRect(0, 0, canvas.width, canvas.height);
  canvas.getContext('2d').drawImage(img, 0, 0, img.width, img.height,
      x, y, img.width * ratio, img.height * ratio);
}

document.querySelector('video').addEventListener('play', function() {
  document.querySelector('#grabFrameButton').disabled = false;
  document.querySelector('#takePhotoButton').disabled = false;
});

Specifications

Specification Status Comment
MediaStream Image Capture
The definition of 'ImageCapture' in that specification.
Working Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 59 ? ? 46 ?
getPhotoSettings() 61 ? ? 48 ?
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile
Basic support 59 59 ? ? ? 46 ?
getPhotoSettings() 61 61 ? ? ? 48 ?

Document Tags and Contributors

 Contributors to this page: FloraFauna, jpmedley
 Last updated by: FloraFauna,