Reconnaissance systems planners need to know the performance of airborne sensor systems. This performance is measured in the quality of the imagery produced. Image quality is almost undefinable and is a complex of physical factors of which one or more are usually measured; such as sharpness, resolution, etc. The Air Force and most of industry rely heavily on measurements of system resolution for specifying and evaluating performance. System resolution, despite its limitations, generally has been easy to measure, readily accepted, proven effective in serially grading lenses, systems, etc., and not known to cause significant errors. The methods usually used by the Air Force to measure resolution are: 1. Tribar Target (RP) Reading 2. Visual Edge Matching (VEM) 3. Maximum Magnification Factor (MMF) 4. Modulation Transfer Function (MTF) All four methods are used when conditions warrant, and where the required equipment is available. Uncertainties between readings are thereby reduced, and the credibility of results increased. The Air Force continues to acknowledge the need for increasing image quality and to improve image quality measurement methods for all of the Air Force Reconnaissance and Mapping sensor systems. The Air Staff, therefore, established project "SENTINEL SIGMA" to improve appropriate emphasis to this effort. Within this program, all image evaluation methods are being evaluated at the Air Force Sensor Evaluation Center (AFSEC) to determine their adequacy of measuring image quality. To date, preliminary tests give a high correlation between VEM and TRIBAR readings.