In order to restore a blurred and noisy image, a filter must be constructed. This requires estimates of the blurring function and the signal/noise-ratio (S/N-ratio). A procedure has been worked out that gives S/N-estimates in practical cases. This signal analysis is performed coherent optically with high precision and it uses the information contained in the power spectra of relevant image details. This article concentrates on the realization of the approach that is illustrated by actual data. Topics such as window functions, γ-correction, scanning devices, and special optical set-ups are treated in detail.