Principles of Image Quality Criteria

The demands on a Abstract The demands on a satisfactory image quality criterion are manifold: 1. to reduce the large number of data ensuing from an exact objective evaluation of an optical system, e.g. by OTF measurements; 2. to take into account specifications of the practical use of the optical system given by object selection and receiver characteristics or image processing units; 3. to be sensitive to variations of image quality which are relevant to the task of the imaging process, and insensitive to variations below a given level; 4. to be easily deduced from measurements and (or) theoretically calculated data. Such a criterion should be able to facilitate the comparison of different systems, to select the most suitable, to take into account the influence of quality variations due to fabrication tolerances, to help to construct the most adequate system by using the crite­ rion as a merit function in automatic correction procedures and last but not least, to open up the possibility of optimizing an "adaptive optic" on line by the adjustment of variable parameters. It is demonstrated how for optical systems, Image Quality Criteria (I.Q.C.'s) can be deduced. Besides the selection of an ideal criterion, reaching agreement on a generally acceptable one and its use is of equal importance for its introduction.