Optimum brightness level and simplified characterization of CRT color monitors

The nonlinear relationship between luminance and DAC count could be charact erized with the simplified model, if optimum brightness level is set. In th is study, we propose a technique to set the optimum level of brightness, in which offsets for RGB channels can be assumed to zero, and determine the g amma coefficients from log-log data without nonlinear optimization. The opt imum brightness level could be found by measuring a few tones of neutral fo r the combination of 3 levels of brightness and 2 levels of contrast. This technique has two advantages, it does not require measurements for 0 DAC co unt, and does not require nonlinear optimization in finding the gamma coeff icient of the display system. Two CRT monitors by different manufacturers h ave been rested. As the result, all monitors could be set to their optimum state with a different combination of brightness and contrast. In that stat e, the gamma coefficient for each channel could be determined from two meas uring data and the tone reproduction characteristics of the RGB channel cou ld be characterized with the simplified equation, neglecting offset and gai n. The accuracy of characterization was better than 0.5 Delta E*(ab) for 12 5 colors for a monitor having good channel independence. (C) 2000 John Wile y & Sons, Inc.