usdImagingGL idiff tests should be able to detect the difference between visibly distinct reference images #1866
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Description of Change(s)
With the current parameters used for the image diff tests in usdImagingGL, the reference images cannot be distinguished from each other: idiff passes many image pairs as "similar enough" even though they are (visibly) distinctly different. Specifically, the Fail parameter of 1 (the most lenient value possible) usually passes every image pair, so tests using that rely solely on the additional Perceptual test. Using a Python script, all pairs of images referenced by each test were compared using idiff to determine reasonable Fail and FailPercent parameters. The proposed change would ensure that for the parameters and reference images of each test, the parameters can at least differentiate between any pair of reference images that differ.
Fixes Issue(s)