OPTIMUM COLOR FILTERS FOR CCD DIGITAL CAMERAS

A procedure for the definition of optimum spectral transmission curves for any solid-state (especially silicon-based CCD) color camera is pr esented. The design of the target curves is based on computer simulati on of the camera system and on the use of test colors with known spect ral reflectances. Color errors are measured in a uniform color space ( CIELUV) and by application of the Commission Internationale de l'Eclai rage color difference formula. Dielectric filter stacks were designed by simulated thermal annealing, and a stripe filter pattern was fabric ated with transmission properties close to the specifications. Optimiz ation of the color transformation minimizes the residual average color error and an average color error of approximately 1 just noticeable d ifference should be feasible. This means that color differences on a s ide-to-side comparison of original and reproduced color are practicall y imperceptible. In addition, electrical cross talk within the solid-s tate imager can be compensated by adapting the color matrixing coeffic ients. The theoretical findings of this work were employed for the des ign and fabrication of a high-resolution digital CCD color camera with high colorimetric accuracy.