Abstract: A method and apparatus for enhancing the contrast of a local area of interest within an electronic image of an object, such as a female breast, which has been transilluminated by non-ionizing radiation such as light or sound. The area of interest may be a cancerous tumor, cyst or another object which differentially absorbs or transmits the radiation. Enhancement of contrast is by normalization of the electronic image. Normalization includes modeling the illumination field of the image to compensate for the non-uniformity of the illumination field, and then combining the modeled field with the original image. Four normalization processes are disclosed: Gaussian curve fitting, geometric mean smoothing, arithmetic mean smoothing, and arithmetic mean smoothing only within the boundary of the local area of interest. Also disclosed is a process for highlighting local areas which are the result of enhanced transmission of the radiation, such as potential cyst sites, and color mapping more than one displayed image.

Abstract: An apparatus for dividing light reflected by an illuminated surface into constituent parts of illuminating light and surface spectral reflectance of the surface. The apparatus includes a receiving device for receiving signals representing measured spectral power distribution Im(.lambda.) of the light reflected by the illuminated surface. The apparatus generates a weighting coefficient .epsilon..sub.i for each of M illuminant basis functions EB.sub.i (.lambda.) for describing the illuminating light. Weighting coefficients .sigma..sub.j for each of N reflectance basis functions Sb.sub.j (.lambda.) are generated to describe the reflectance of the surface. The apparatus compares an approximation Ia(.lambda.) of the measured spectral power distribution Im(.lambda.), Ia(.lambda.) being defined by the relation: ##EQU1## where the set of product pairs Eb.sub.i (.lambda.)Sb.sub.j (.lambda.) is linearly independent.Different weighting coefficients are regenerated until said Ia(.lambda.) and said Im(.lambda.