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The definition of contrast in a complex scene is a long-standing problem. The local contrast in an image may be approximated by the contrast of a Gabor patch of varying phase and bandwidth. Observers' perceived (apparent) contrast, as indicated by matching of such patterns, were compared here to the physical contrast calculated by a number of definitions. The 2 c/deg 1-octave Gabor patch stimuli of different phases were presented side by side, separated by 4 deg. During each session the subjects (n = 5) were adapted to the average luminance, and four different contrast levels were randomly interleaved. The subject's task was to indicate which of the two patterns was lower in contrast. Equal apparent contrast was determined by fitting a psychometric function to the data. The results of the matching rejected the hypothesis that either the Michelson formula or the King-Smith and Kulikowski contrast metric (C _KK …