| 
  | perceptual_diff(std_image,
        test_image)
   |  |  Run Perceptual Diff to compare a test image to a standard. The workup requires access to the shared installation of Perceptual 
  Diff in /nfs/software/lib/<platform>/. It expects host-specific std
  images to be located in a subdirectory of the test named 
  references/<hostname>/. For example, for the host 
  pdx-desk-l03.schrodinger.com, refeerences are expected in 
  stu_<testid>/references/pdx-desk-l03.schrodinger.com/. usage: custom.perceptual_diff.perceptual_diff(std_image, 
  test_image) 
   |