The measurement is also described in the Qualification thread.
The objective metrological assessment of the monitor is carried out using a photometer in cd/m². Before the first measurement, the monitor should have been in normal operation for approx. 30 minutes, e.g. during normal practical use.

During the first measurement (2), a black image with DDLmin is displayed on the monitor, or the black area at (f) of the test image is measured. The measuring head of the measuring device is placed directly on the monitor. The measured value is noted in the table.
For the second measurement (3), a white image with DDLmax is displayed on the monitor, or the white area at (f) of the test image is measured. The measuring head of the measuring device is placed directly on the monitor. The measured value is noted in the table.
Before the third measurement (1), the monitor is switched off. The measuring head of the measuring device is held at a distance of 250 mm from the monitor, pointing at the monitor, and the measured value is noted in the table under Lamb.
The total minimum luminance L'min is calculated from Lmin + Lamb. The total maximum luminance L'max is calculated analogously from Lmax + Lamb. The maximum luminance ratio r' is calculated as the quotient of L'max / L'min. The calculated values are entered in the table.
Finally, the illuminance E in the room is measured in LUX using the illuminance meter. To do this, the head of the measuring device is aligned perpendicular to the monitor at a distance of 1 m from the dark monitor and the measured value is noted in the bottom row of the table (7).
The results are compared with the limit values for the application class entered in the table. If there are deviations of more than 20% in any of the measured values, error correction measures must be initiated.