An Evaluation of MTF Determination Methods for 35mm Film Scanners

Three different techniques were used to determine the Modulation Transfer Function (MTF) of a 35mm film scanner. The first involved scanning sine wave charts comprising a number of patches with different frequencies of known modulation. The second method involved the scanning and Fourier transform of a photographic grain noise pattern to simulate low modulation white noise. Finally, the ISO 12233 Slanted-edge Spatial Frequency Response (SFR) plug-in was used to determine the average MTF of the device. This creates a super-sampled edge profile from sequential scan-lines of the sampled image of an edge. Procedures for creating test targets, where appropriate, are described. Advantages and limitations encountered in applying each methodology are discussed, as well as the precision of each method for deriving the MTF. Conclusions are drawn concerning the comparability of MTFs determined by the three methods.