Advantech IDK-121R-42XGA1 User Manual page 37

Note2 Definition of 5 points position (Display active area: 246mm (H) x 184.5mm(V))
Note3 The luminance uniformity of 5 points is defined by dividing the minimum
luminance values by the maximum test point luminance.
Note4 Definition of contrast ratio (CR):
Note5 Definition of response time:
The output signals of photo detector are measured when the input signals
are changed from "White" to "Black" (falling time) and from "Black" to "White"
(rising time), respectively. The response time interval is between 10% and
90% of amplitudes. Please refer to the figure as below.
Note6 Definition of viewing angle
Viewing angle is the measurement of contrast ratio 10, at the screen center,
over a 180° horizontal and 180° vertical range (off-normal viewing angles).
The 180° viewing angle range is broken down as below:
90° () horizontal left and right, and 90° () vertical high (up) and low (down).
The measurement direction is typically perpendicular to the display surface
with the screen rotated to its center to develop the desired measurement
viewing angle.
31 IDK-1112R User Manual