title: Combining two images on one canvas in HTML5
body: <p>I'm working with the HTML5 canvas element. Let's say I have 2 ImageData objects that I want to combine to be able to put on one canvas. Lets assume that I don't care how these images combine. Both ImageData objects have the exact same pixel count and shape.</p>
  
  <p>What's the best way to combine the two images?</p>
  
  <p>I figure that I can write a for loop and iterate over the ImageData array and manually combine and set every rgba value per pixel, but I'm wondering if there's a better way?  I need this operation to happen as quickly as possible.</p>
  
  <p>Thanks in advance.</p>