The variance of a bar pattern image can be used to measure the modulation transfer function (MTF) of an imaging system. This method is often simpler and more practical than conventional methods. The theoretical basis of the method is derived, and verification is provided by computer simulations. The computer simulations also are used to evaluate the accuracy of approximate formulas. The MTF of a computed tomographic (CT) scanner is measured to illustrate the technique.
Ronald T. Droege,
Mark S. Rzeszotarski,
"Modulation Transfer Function From The Variance Of Cyclic Bar Images," Optical Engineering 23(1), 230168 (1 February 1984). https://doi.org/10.1117/12.7973255