SET-THEORETIC ESTIMATION IN COLOR SCANNER CHARACTERIZATION

A set theoretic approach for the spectral characterization of a color scanner is described. These devices usually employ three channels to o btain a device dependent RGB (red, green, blue) image. To display/prin t an image, the device dependent RGB values must be correctly transfor med to the color space of the target device. To determine accurate and efficient transformations for a number of devices, knowledge of the s pectral sensitivity of the scanner is essential. Direct measurement of the sensitivity requires a set of expensive narrow band reflectances and is often infeasible. Methods that estimate the spectral sensitivit y based on measurements with typical reflectance samples are therefore of interest. Due to the low dimensionality of the space of object ref lectance spectra, this is a highly ill-conditioned problem. As a resul t, conventional estimation techniques that fail to take a priori knowl edge into account perform rather poorly on this problem. A set theoret ic approach that incorporates available a priori knowledge into the es timation framework yields better results. Results are presented for a simulated scanner characterization problem and for an actual character ization to demonstrate the increased accuracy compared with convention al methods. (C) 1996 SPIE and IS&T.