OpenImageIO/oiio — pull request #500 by lgritz (2013-01-31 20:47:13+00:00)
Title: Bug fix in wrap_periodic_sharedborder (used by environment call with exr maps)

The math here made an assumption that the amount of periodic wrapping could
be no more than 1 cycle. But it could! If using a bicubic lookup (needs 4
samples) at a MIP level with resolution <= 2 (very blurry), you could
mis-calculate the wrap and end up with a coordinate out of the range of
valid pixels.