title: ImageMagick NOT TO CONVERT PNG bit depth
body: <p>I have following batch script for adding transparent color to images, it is working nicely for that</p>
  
  <pre><code>for /f %%f in ('dir /b .') do convert %%f -transparent white tra/%%f
  </code></pre>
  
  <p>However it automatically converts bit-depth of image to 8 bpp or less if applicable. And I don't want that. Tried "-depth 32" and "-define png:bit-depth=value=32" but no luck, imagemagick still converts image to lower bit depth. 
  Any help please?</p>