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


- White Point Calibration in the Frame Buffer



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S-52 Appendix 2 - IHO
S-52 Appendix 2 - IHO
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White Point Calibration in the Frame Buffer: Use an interface to the computer keyboard or trackball) that allows the technician to adjust the white point by adjusting the maximum output of the DAC's to yield a white that compares with the standard. The computer will then adjust the DAC values in the middle of the range appropriately to maintain colour fidelity.
1. Put a white signal in the screen.
2. Adjust the input signal levels (DAC values) of red, green, and blue to give the correct white level.
3. Instruct the computer to compute the DAC value corrections in the range. C Automatic Calibration monitors Several manufacturers make monitors's that have builtin calibration capability. (e.g.
Barco). These monitor's will perform a white point calibration by adjusting internal controls through the use of their own light sensor and calibration system. This recalibration process is in general suitable for the white point touch-up requirements of this Annex.

S, Edition 6.0 March 2010 84 C Complete calibration Calibration and adjustment beyond the white point adjustments are the domain of a more detailed and complex procedure, and are not practical to undertake on the Bridge. Under normal conditions, when a display fails the white balance test or cannot be corrected by a white balance adjustment, it should be returned to the factory for re-calibration and/or repair. (See Annex B Procedure for Initial Calibration of Colour
Displays.)
This Annex was researched and written by Matthew Cowan
18 McAllister Lane Bloomingdale, Ontario under a contract funded by The Canadian Coast Guard. The Grayscale Test was suggested by Dave Hannah, Kelvin Hughes Limited, Ilford, Essex, UK. This annex was amended as generic for any type of monitor by
Hannu Peiponen, Furuno Oy, Espoo, Finland.
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