A summary is presented of current work on applying the optical power spectrum to measurements of photographic images. Conclusions are that the technique is useful for characterization information content of images and is predictably sensitive to focal errors and contrast degradation.
Robert R. Shannon,
"Application Of Signal-To-Noise Concepts To Optical Power Spectra", Proc. SPIE 0117, Data Extraction and Classification from Film, (22 November 1977); doi: 10.1117/12.955654; https://doi.org/10.1117/12.955654