Setting the Contrast Control: The contrast control should be adjusted to achieve maximum required output level at full white signal. Using a luminance meter and a peak white signal, (DAC values of 255, 255, 255) adjust the contrast control for the maximum luminance required by the system. Lock this control for the remainder of the calibration process. C White point touch-up On the first order, the colour shifting will be primarily caused by white point shifts. Calibration can be maintained by 'touching up' the white point on a periodic basis. This can be done by a CRT technician who adjusts controls inside the CRT, or can be performed by adjusting the colour DAC values through an adjustment and calculational process. (The DAC adjustment would have to be designed into the software system by the ECDIS manufacturer.