AV Tags</a></td></tr>
</table></td></tr></table></blockquote>

<h2><a name='ALPH'>RIFF ALPH Tags</a></h2>
<p>WebP alpha chunk.</p>
<blockquote>
<table class=frame><tr><td>
<table class=inner cellspacing=1>
<tr class=h><th>Index1</th><th>Tag Name</th>
<th>Writable</th><th>Values / <span class=n>Notes</span></th></tr>
<tr>
<td class=r title='0 = 0x0'>0</td>
<td>AlphaPreprocessing</td>
<td class=c>N</td>
<td><span class=s>[Mask 0x03]
  <br>0x0 = none
  <br>0x1 = Level Reduction</span></td></tr>
<tr class=b>
<t