Optical image processing by matched amplification

An image-processing technique, which we call matched amplification, is proposed and demonstrated. Analogous to the well-known technique of matched filtering, matched amplification manipulates an input image at its Fourier plane by using a Fourier transform of a reference image. In matched amplification, however, the Fourier components of the input image that matchthose of the reference image are amplified rather than attenuated as in the case of matched filtering. Owing to this amplification process, matched amplification is advantageous for applications that require cascadability, high energy efficiency of the processed image, or large intensity dynamic range of the input image. We show experimental results using photorefractive two-beam coupling in BaTiO(3) as the coherent amplification stage.