Coherent optical power spectra of random scene imagery can become a powerful image evaluation technique when properly analyzed. A normalized low order moment of power spectra is set forth as a good image quality merit factor, which also has the advantageous property of taking out the spectrum analyzer’s aperture effect. In addition to the relevant theory, experimental results with this merit factor of power spectra are given that demonstrate a high degree of correlation with subjective quality rankings, as well as the accurate assessment of optimum focus.
Norman B. Nill, "Scene power spectra: the moment as an image quality merit factor," Appl. Opt. 15, 2846-2854 (1976)