std.PEMVerifier(clip clip[, float[] upper, float[] lower])

The PEMVerifier is used to check for out-of-bounds pixel values during filter development. It is a public function so badly coded filters won’t go unnoticed.

If no values are set, then upper and lower default to the max and min values allowed in the current format. If an out of bounds value is encountered a frame error is set and the coordinates of the first bad pixel are included in the error message.