title: TypeError: color must be int or tuple
body: <p>I'm trying to arrange faces detected by opencv face_cascade in a contact sheet. The following code produces this error: &quot;TypeError: color must be int or tuple&quot;, which traces to the last line below. Does anyone know what's causing this error?</p>
  <pre><code>contact_sheet_size = (640, height * 128)
  contact_sheet = Image.new(mode ='RGB', size = contact_sheet_size)
  x, y = 0, 0
  for face in faces_detect:
      cropped = resized_images[image_no].crop(box = (face[0], face[1], face[2], face[3]))
      contact_sheet.paste(cropped.thumbnail(size = (128, 128)), (x, y))
  </code></pre>
  <p>The resized_images are PIL.Images.Image's.</p>
  <p>Full traceback:</p>
  <pre><code>Traceback (most recent call last):
    File &quot;../approach.py&quot;, line 147, in &lt;module&gt;
      contact_sheet.paste(cropped.thumbnail(size = (128, 128)), (x, y, 128, 128))
    File &quot;..\venv\lib\site-packages\PIL\Image.py&quot;, line 1506, in paste
      self.im.paste(im, box)
  TypeError: color must be int or tuple
  </code></pre>