Nonlinear Detection And Estimation Of Images Degraded By Film-Grain Noise
F. Naderi, Alexander A. Sawchuk · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1976
Taking into account the chemical and optical degrading factors as well as the granularity noise results in a subjectively reasonable mathematical model for the formation and recording of photographic images. This model represents highly nonlinear observations, making the subsequent restoration difficult. When images are scanned with very small apertures on a microdensitometer, the noise is so severe that conventional estimators do not perform well. In these cases detection schemes suited to individual degraded pictures are much more effective. When the noise is not so severe, an adaptive minimum mean square error filter can be applied. This filter explicitly includes the nonlinear image formation effects and does not require the assumption of stationary image statistics.