International hydrographic organization specifications for chart content and display aspects of ecdis


C.4 Re-calibration of the Monitor



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S-52 Appendix 2 - IHO
S-52 Appendix 2 - IHO
C.4
Re-calibration of the Monitor
Recalibration of the monitor should be performed by a knowledgeable monitor technician, who has experience of light measurement.
Two levels of calibration can be performed White Point Touch-up and Complete. Before undertaking either calibration procedure, it is necessary to set and lock the controls for the duration of the calibration
Setting the Controls: The Brightness control is used to adjust the black level of the monitor. This is the point where the monitor screen is seen as black, and this setting will create the blackest black that can be displayed. After the control is set, it must be locked in place. Any adjustment of the brightness setting after calibration invalidates the process, unless it is returned to its calibrated position, (e.g. a detent position. With the monitor in a dark environment (accomplished either at night or with the monitor area darkened with a hood, and with the monitor turned on and warmed up to the manufacturer's specification, drive the monitor with a black signal (0, 0, 0). Observe the border around the CRT where the tube is normally black, and visually compare its intensity to the black square in the centre of the screen. First adjust the brightness control to its maximum, then adjust it down until there is no distinction between the black square and the background. Adjust the control up until the active area just shows. (If a luminance meter is available, measure the Luminance of this area. It should be less than 0.52 candelas per square metre. Lock the control for the

S, Edition 6.0 March 2010 83 remainder of the calibration process.

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