Elimination of microdensitometer degradation from scans of photographic images.

In microdensitometry, the tracing of a knife edge does not yield a step function. Therefore, when a photographic image is traced the result is not a spatially true representation of the image. A computational procedure has been developed that corrects for microdensitometer effects. This is achieved by obtaining the inverse Fourier transform of the reciprocal values of the microdensitometer modulation transfer function and convolving the resulting function with the digital output of the microdensitometer scan. The result is the corrected scan data for the photographic image. This technique has been applied successfully to edge gradient analysis for both analytic and experimental edges. The compensation for microdensitometer degradation should have a number of applications.