COLOR AND LUMINANCE CONTROL SYSTEM FOR LIQUID CRYSTAL PROJECTION DISPLAYS

A liquid crystal display ("LCD") projection unit (12) employs a luminance and color balance system having a lookup table (100) storing multiple sets of gain and/or gamma corrected responses (92-99) for color balance and luminance control. The lookup table values are determined by measuring an S-curve response (90) of an LCD array (40) for each of a set of R, G, and B input data values, converting the S-curve responses to a corresponding set of gamma responses, and scaling the gamma responses to generate red ("R"), green ("G"), and blue ("B") families of gain and gamma corrected values. Color balance is adjusted by selecting the particular R, G, and B families of gain and gamma corrected values that cause the LCD projection unit to match a predetermined ratio of maximum R, G, and B luminance values. Luminance is adjusted by selecting families of lookup table values that adjust the transmittance of the LCD while maintaining the color balance. The LCD projection unit achieves a uniform luminance and color balance that renders it suitable for use in a multiscreen display system (10).