title: Find input image (ID,passport) in imagesDB based on similarity
body: <p>I would like to decide if an image is present in a list stored in a DB (e.g. pictures of IDs, passport, Stu. card, etc). I thought about using a KNN algorithm, that will plot the K closest images. </p>
  
  <p>Options for distance metric:</p>
  
  <ol>
  <li>sum of Euclidean distance between each relative pixels (img1[pixel_i], img2[pixel_i])</li>
  <li>sum of Euclidean distance betwen <em>each</em> pixel to each other, multiplied by some factor decreasing with distance (pixel to pixel)</li>
  <li>same as above, but with manhattan...</li>
  </ol>
  
  <p>Do you know/think of a better way to deal with the image similarity subject?</p>