Identification

This term (along with Detection and Recognition) is one of three terms commonly used to describe an imaging system task. In this context, Identification means that the observer can differentiate small differences between targets of the same class. For example, determining whether a human target (the class of target) has a rifle or a shovel in their hand (the small difference between targets within the same class). Each of these tasks is best described statistically; since these terms historically refer to a human observer’s ability to accomplish the task. How well the tasks can be accomplished in a given situation is described in terms of what fraction of average observers could accomplish it, within the given conditions. For example, “50% Probability of Identification” (sometimes written as P(ident)_50%) means that 50% of an average group of observers would say that they can identify small differences between targets of the same class within the image. According to the Johnson Criteria, it takes 12 pixels across the critical dimension of the target to achieve the 50% level of identification. See also Critical Dimension.