A method of representing a color image comprises selecting a region of the image, selecting one or more colors as representative colors for the region and, for a region having two or more representative colors, calculating two parameters for each representative color including the variance of the color distribution of the image and the color space value and using these parameters to derive descriptors for the image region.
Techniques for estimating an average background value and an average foreground value of an image data formed by a plurality of pixels by selecting a first plurality of pixels forming a first calculation window from the plurality of pixels, determining at least first, second and third statistical moments for the first plurality of pixels, and determining at least one of average background value and average foreground value using the at least first, second and third statistical moments determined for the first plurality of pixels.
