title: Flutter convert image to binary data
body: <p>How can i covert Image file to binary data ?
  I'm using a library call  image_picker for pick the image from gallery or camera.
  And I want to convert the image that I picked to binary data.</p>
  
  <pre><code>File image = await ImagePicker.pickImage(source: ImageSource.gallery)
  (image as Image).toByteData // the method toByteData here is not pop up.
  </code></pre>