Methods of Appraising Photographic Systems: Part I—Historical Review

Reasons for the unsuitability of resolving power as a criterion of the performance of an optical or photographic system in general are outlined and the newer concepts of acutance and spread function are introduced. The method of computing the edge trace from the spread function is described. The procedure known as convolution is introduced and exemplified by computing the image of a sinusoidal test object. It is shown that such an image is also sinusoidal and of the same frequency as the object but of different modulation and phase and that the properties of such an image give rise to the concept of sine-wave response.