The effect of the flux prior on the decision boundaries of Bayesian SED-matched source detection. The exponential scale factor α affects the shape of the decision contours. Decision contours for three different false-positive rates are shown (10⁻¹, 10⁻⁴, and 10⁻⁷) for two different “alpha” values (“bright”: α = 1; “faint”: α = 4). The foreground model is the three-SED model used in previous figures. The detailed shape of the decision boundary is affected by the flux prior.