Comparison of Two MTF Measurement Methods: Sine-Wave Vs Edge Gradient Analysis

A comparison of the sine-wave and edge gradient MTF measurement methods, on a photographic black and white film, was performed. A statistical test, a CMT acutance test, and a graphical comparison showed that there was no significant difference between the two measurement methods. This was true for the film processed to have large adjacency effects, as well as for the film processed to have no adjacency effects; however, the agreement was slightly better for the latter process. The research also showed that aligning the midpoints of the edge traces, normalizing the individual edge traces, and then averaging several edge traces significantly reduced grain noise, and produced a superior representative edge for MTF analysis. A new adaptive damping filter also proved quite successful in the suppression of grain noise without degrading the MTF measurement. The combination of averaging several edge traces, and then using the adaptive filter, produced excellent MTF results from the edge traces