title: Remove alpha compositing knowing the watermark (revert/compensate)
body: <p>I have watermarked a bunch of images image with PIL (PILLOW in fact).</p>
  
  <p>I have the original watermark and I know exactly how it has been resized and pasted on the image (0.75 opacity). The watermark is essentially black, white and red.</p>
  
  <p>I want to restore images as close as possible as they were originally.</p>
  
  <ul>
  <li>Is there any chance I could do that automatically?</li>
  <li>What about quality? Is it worth it? Do you have examples of the result of such a process?</li>
  </ul>
  
  <p>If so, how would I manage to do this?</p>
  
  <p>Here is the code I used to watermark the image:</p>
  
  <pre><code>logo = Image.open(path)
  red, green, blue, alpha = logo.split()
  alpha = ImageEnhance.Brightness(alpha).enhance(0.75)
  logo.putalpha(alpha)
  
  img = Image.open('...')
  img = Image.composite(logo, img, logo)
  </code></pre>