Photorefractive two-beam coupling optimal thresholding filter for additive signal-dependent noise reduction

Computer simulations of photorefractive thresholding filters for the reduction of artifact or dust noise demonstrate an increase in signal-to-noise ratio (SNR) of 70% to 95%, respectively, of that provided by the Wiener filter for inputs with a SNR of approximately 3. These simple, nearly optimal filters use a spectral thresholding profile that is proportional to the envelope of the noise spectrum. Alternative nonlinear filters with either 1/ν or constant thresholding profiles increase the SNR almost as much as the noise-envelope thresholding filter.