title: Distance between 2 pixels
body: <p>Coming from software development, i'm new to image processing.
  I try to get the distance between two pixels in an image that is a numpy array of shape (100, 100, 3).</p>
  
  <p>For example i want to find the distance between a pixel blue (0, 0, 255) and a pixel red (255, 0, 0) in the image, I tried with a for loop or np.where() ... but no success.
  The distance could be the some kind of difference between the two indexes in the image (possibility that there is more pixels of these colors so at least the first met in the image)</p>
  
  <p>Any idea how to do that ?</p>
  
  <p>EDIT:
  I'm capturing part of my screen like that:</p>
  
  <pre><code>screen = np.array(pyautogui.screenshot(region=(80,120,100,100)))
  </code></pre>
  
  <p>Now i want to find the pixel(s) of color blue and the pixel(s) of color red and the distance between them in the image</p>