sp800_76Test_15a/b: The excel requirements don't match the coded test

[MKSCertiPath]

Excel says:
a: Width of the Size of Scanned Image in x direction is the larger of the widths of the two input images.
b: Height of the Size of Scanned Image in y direction is the larger of the widths of the two input images.

The code says and implements:

a: Confirm that scanned image in X are non-zero (and obtained from enrollment records??)
b: Confirm that scanned image in Y are non-zero (and obtained from enrollment records??)

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