1. A method to determine the probability of detection of a target of interest, comprising the steps of: (a) acquiring a set of imaged scenes containing the target, the acquiring step consisting either of directing an infrared imaging device at the scenes or graphically constructing the scenes, the acquiring step including making representations of the scenes; (b) pixelating the representations of any of the scenes not pixelated during the acquiring step; (c) recording the representations in a memory; (d) dividing the representations into target blocks of pixels and background blocks of pixels; (e) after dividing the representations into the blocks, using a plurality of .DELTA.T metrics to derive a plurality of .DELTA.T values for the scenes; (f) deriving relative .DELTA.T values from the plurality of .DELTA.T values; (g) dividing the representations into cells of pixels in accordance with a plurality of clutter metrics; (h) after dividing the representations into cells, use the plurality of clutter metrics to derive a plurality of clutter values for the scenes; (i) deriving relative clutter values for the scenes; (j) using the relative .DELTA.T values and the relative clutter values in determining the probability of detection of the targets of interest in the scenes; and (k) based on the probabilities of detection choosing the optimum scene or set of scenes.