[webkit-dev] How to deal with 1-pixel differences in reftests ?
Carlos Alberto Lopez Perez
clopez at igalia.com
Wed Nov 18 04:36:34 PST 2015
Some reference tests give a 1-pixel or very few pixel differences .
I'm not sure if this really indicates a problem in the WebKit code, or
it indicates that we are just too strict not allowing even a very small
percentage in pixel differences for this kind of tests.
Should we tolerate a few pixel differences for reftests ?
I have done some tests, and the test in  passes for any value of
tolerance >= 0.00001% (with the GTK port).
I'm inclined to allow a very small value, for example a 0.001% (that
would be 100 times stricter than the tolerance value we use for the
For example, this is happening in the GTK port:
The diff image normalized (so you can see where is the diff):
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