Correlation of color components of camera output signal and decorrelation methods

Abstract

Typical single-chip CCD co0lor camera provides output signal containing RGB components of acquired image. Strong inter- channel correlation of that signal, unacceptable for some applications, is shown. Therefore, some kind of RGB color space transform is required to decrease this correlation. Only the Karhunen-Loeve transform (KLT) secures compete decorrelation. However, possible applications of this method are limited by the fact that coefficients of transform matrix must be calculated for each image separately. In the paper details of effective implementation such transform of color images are described. The examples of KLT applications in the field of color image processing are quoted. Using the standard color images, principal properties of KLT are shown, i.e. a complete decorrelation of color components and energy compaction in first components. This paper present also an approach that allows determining KLT coefficients that are constant for certain class of images and guarantee complete decorrelation simultaneously. A methodology for finding these coefficients is briefly described and some remarks on criteria of image selection for this class are made.