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To ensure accurate color reproduction, displays are characterized to map between device-independent XYZ values to device-dependent RGB values. The characterization is composed of two parts, a linear transformation and a non-linear LUT table. Both can be estimated by measuring triplets of digital counts with a colorimeter. An LMT colorimeter is used to characterize displays due to its high sensitivity even at low luminance level. The characterization procedure is different from display calibration in that display calibration involves changes made to the display itself, while characterization does not. Therefore, color reproduction will not be improved if a poor display is used. For more details, see Day, et al. 2004. |
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Tristimulus values for verification :
After characterization, a validation is performed to test the color reproduction accuracy of the display. A group of tristimulus values is selected as target values, and they are converted to device-dependent RGB values by the display characterization model. These RGB digital counts are input to the display, and a LMT colorimeter is used to measure the output color by the display. The measured and target XYZ values are then compared to calculate the color difference to evaluate the reproduction accuracy.
The blue diamonds are the Y/B (yellow/blue) series of chromaticity values, and the red rectangles are the R/G (red/green) series of target chromaticity values.
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Verification results of chromaticity:
An Apple Cinema Display is used for characterization. The overlap between the measured and target chromaticity values indicate an accurate reproduction in color (chromaticity).
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Verification results of luminance:
An Apple Cinema Display is used for characterization. Overall the measured luminance values match with the target ones, indicating an accurate reproduction in color (luminance).
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