The subject of imagery evaluation as it applies to electro-optical (EO) sensor performance testing standards is discussed. Some of the difficulties encountered in the development of these standards for the various aircraft Line Replaceable Units (LRUs) are listed. The use of system performance testing is regarded as a requirement for the depot maintenance program to insure the integrity of total system performance requirements for EO imaging systems such as the Advanced Tactical Air Reconnaissance System (ATARS). The necessity for tying NATO Essential Elements of Information (EEIs) together with Imagery Interpretation Rating Scale (IIRS) numbers is explained. The requirements for a field target suitable for EO imagery evaluation is explained.