DYNAMIC-RANGE COMPRESSION OF IMAGES BY 2-WAVE MIXING IN PHOTOREFRACTIVE MATERIALS

We propose and demonstrate a method for the dynamic-range compression of images using two-wave mixing in photorefractive materials. This met hod, in which an image is carried on the signal beam, permits a certai n amount of control over the shape of the input and output curves by t he variation of the pump intensity, the coupling constant, and the tim e at which the output image is examined. We also discuss the possible option of adding a feedback loop from the output image so that the ran ge compression can be adapted to suit the intensity profile in the inp ut image.