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            <b><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - test/cairo-test-suite reports wrong max diff comparing different opaque images"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=84044#c3">Comment # 3</a>
              on <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - test/cairo-test-suite reports wrong max diff comparing different opaque images"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=84044">bug 84044</a>
              from <span class="vcard"><a class="email" href="mailto:sixtysix@inwind.it" title="Massimo <sixtysix@inwind.it>"> <span class="fn">Massimo</span></a>
</span></b>
        <pre>(In reply to Uli Schlachter from <a href="show_bug.cgi?id=84044#c2">comment #2</a>)
<span class="quote">> Isn't the bug here really in the code that compares the images?

> You are blaming test/buffer-diff.c line 80 which is:

>    if ((row_a[x] & mask) != (row_b[x] & mask))
> </span >

I blamed test/buffer-diff.c because when that condition is
TRUE, the maximum diff computed includes also the non-alpha
channel:

<a href="http://cgit.freedesktop.org/cairo/tree/test/buffer-diff.c#n85">http://cgit.freedesktop.org/cairo/tree/test/buffer-diff.c#n85</a>

So my first observation was reading a test log in which
two identical images (argb32 and rgb24) had reported two
max diff values compared to the same reference.

yes, there are also other bugs in test/pdiff</pre>
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