Controling color of liquid-crystal displays

Two newly derived characterization models for a liquid-crystal (LC) display have been tested for five LC-based displays. Data measured from a series of test colors indicated that all LC-based displays showed similar characteristics, including an S-shaped tone curve and poor channel chromaticity constancy. Because they include a hyperbolic function in their definition, the models do not have analytical inverses, and so iterative mathematical techniques are applied. It was shown that a new characterization model based on a hyperbolic function fits the tone curve very accurately with only four coefficients per channel for any type of LCD. In addition, it was also shown that the first derivative of the function provides a means of accurate correction of the chromaticity variation.