NEC SpectraView 2190 User Manual page 29

SPECTRAVIEW II - USER'S GUIDE | 
Contrast Response
Max error - shows the highest percentage error deviation from the Barten Model curve, as well as the JND
Index of the highest error point.
Show Barten Model - shows the Barten Model curve on the graph. The Barten Model curve is calculated
based on the measured Intensity (white luminance) and black level values.
Show 10% Limits - shows two lines representing 10% error deviations from the Barten Model curve. Medical
displays used for Primary Class image viewing should be within the 10% deviation curves.
Show 20% Limits - shows two lines representing 20% error deviations from the Barten Model curve. Medical
displays used for Secondary Class image viewing should be within the 20% deviation curves.