Now the detection heuristic has changed, the old value is no longer
valid.
Some example thresholds for known mipmap effects that should trigger:
SMG's lava has a mimimum difference of ~17.8, SMG2's clouds have a
minimum difference of ~14.8, and Wind Waker's foam has a minimum
difference of ~15
Non-triggering examples were tested and all had a calculated difference
lower than 3.
So a value of 14 should lean towards false-negatives instead of
positives, but this is clearly incomplete testing and may require
further tweaks later.