Abstract: Methods of electronically enhancing one or more color components (C, Y, M) which together represent the chromatic components of a pixel of an image are described. The methods comprise subtracting from each color component respective quantities which when combined correspond to a grey level (4) to generate reduced color components. These reduced color components are then multiplied by a factor and the modified reduced color components are then added back to the subtracted quantities or to the original color components to generate enhanced color components (13,14), whereby the factor is chosen such that the hue of the original pixel is not substantially changed after enhancement. In one method, the magnitude of the maximum reduced color component is determined and a factor is chosen which is related to the determined magnitude. In another method, the color components are ranked in order of magnitude and compared to derive two equivalent color component values.

Abstract: The invention relates to methods and apparatus for interpolating between coarse stored data to achieve a more accurate answer, and is particularly applicable to color scanning reprographic equipment. Color scanners (5) analyze an original to obtain digital signals (8) representing three primary color intensities. The values for the intensities of each of four printing colors, including black, are functions of all three primary color intensities, and a limited quantity of these sets of four values is stored in a three dimensional matrix (25), consisting of cubes with values at their corners. To obtain values from these coarse stored data corresponding to a point (P) within a cube, an interpolator (26) determines which one, of the three pyramids (e.g. W B G C V in FIG. 2) comprising the cube, contains the point, and interpolates within that pyramid between the values at its five vertices.