title: how to compare similarity between two color images?
body: <p><img src="https://i.stack.imgur.com/sjOwY.png" alt="two image side by side (please ignore the red line in between"></p>
  
  <p>I want to compare how close these two images are (red in similar area), but I can't go pixel by pixel because their color locations are not exactly the same. Anyone know what would be a good approach here?</p>
  
  <p>Thanks,</p>