Edge operator error estimation incorporating measurements of CCD TV camera transfer function

摘要

A method for measuring the two-dimensional modulation transfer function of an image acquisition system with a CCD TV camera input device is presented. The measurements are then used in the estimation of the image edge operator performance. A high resolution edge profile is assembled after the analysis of many profiles from the image of a step. Modulation transfer function measurements beyond the system's Nyquist limit have been obtained. A minimum of apparatus is required. The performances of several systems have been compared. The band limiting of spatial frequencies are considered with respect to signal aliasing, matching components, feature representation and image operator accuracy. The results indicate the efficiency of the system aliasing and reconstruction filters, differences in the vertical and horizontal responses of CCD arrays, and that the rectangular CCD element shape has not deflected the shape of the two dimensional modulation transfer function. Various edge operators have been tested and compared using high resolution edge spread function data computed during the transfer function measurements. These data were from realistically smoothed edges and represent the most difficult edges that the practical system would need to detect. Significant differences were found between results using the traditional pixel average and the new step edge models, indicating that in some cases a simpler, more computationally efficient operator may be sufficient.