Pseudo-color Reduction by Signal Processing for Single-Imaging Device Color Cameras with Primary Filter

Abstract

Three structures of the CCM (Correlative Coefficient Multiplying) interpolation method that produce interpolation signals from other color elements were examined for single-imaging-device color cameras. They are (1) vertical interpolation by three of the horizontal element's lines, (2) horizontal interpolation by three of the vertical element's lines, and (3) adaptive interpolation, which selects either the vertical or horizontal interpolation signal, depending on the direction of the object's gradient. The third method perfectly reduced pseudo-colors on a monochromatic object. The SNR of the differential power signal between a 3-CCD camera and single-imaging-device color camera was improved by 8-12 dB compared with the conventional linear interpolation method at monochromatic objects. When an optical low-pass filter was used, the pseudo-color on a monochromatic object was reduced effectively by the first or second method.