title: ImageMagick convert gif with transparency problem
body: <p>I wrote a script to add watermark to images on my site. Everything works ok for png/jpg, but gif images must be treaten by more complicated way. My script:</p>
  
  <pre><code>convert -splice x36 -gravity south -background white image.gif \
  -coalesce -gravity SouthEast -geometry +0+0 -background white \
  null: watermark-text.png -layers composite new-image.gif
  </code></pre>
  
  <p>For 95 percent of gif it works fine. But there are some examples, that brings errors.
  Concern this image:
  <img src="https://i.stack.imgur.com/sl8Xl.gif" alt="image"></p>
  
  <p>Normal cat. Only first frame contains background (viewed layers in gimp).</p>
  
  <p><img src="https://i.stack.imgur.com/s6qP7.gif" alt="enter image description here"></p>
  
  <p>This is not normal cat. Any suggestions?</p>