title: PIL paste image with alpha appears faded
body: <p>I am working with multiple images that I would like to stack on top of each other to create a single image. However, in working with them, I'm noticing that if the image already has transparency (alpha != 255), that part of the image appears faded. If there is no transparency, all is good.</p>
  
  <p>I saved one of the images I was working with to a PNG and created a small bit of code that duplicates the problem. Essentially, I'm creating a new image with a transparent background and then pasting the image on top:</p>
  
  <pre><code>from PIL import Image
  
  img=Image.new('RGBA', (946,627), (0,0,0,0))
  overlayImage = Image.open('drawing.png')
  img.paste(overlayImage, (0,0), overlayImage)
  img.save('drawing-pasted.png')
  </code></pre>
  
  <p>When this completes, drawing-pasted.png looks like this:</p>
  
  <p><img src="https://i.stack.imgur.com/GPQaN.png" alt="drawing-pasted.png"></p>
  
  <p>But the original drawing (drawing.png) looked like this:</p>
  
  <p><img src="https://i.stack.imgur.com/JwelU.png" alt="drawing.png"></p>
  
  <p>(Images cropped manually to show detail.) The original image circles fill color has an alpha value of 179.</p>
  
  <p>Has anyone else encountered this, and what am I doing wrong? </p>
  
  <p>Thanks much.</p>