The constrained phase congruency feature detector: simultaneous localization, classification and scale determination

Abstract A novel feature detector — the Constrained Phase Congruency Transform (CPCT) is introduced. It simultaneously detects interest points together with their scale in various orientations. Each interest point is detected due to a (possibly imperfect) symmetry (or anti-symmetry) around it. The scale of the symmetry (or anti-symmetry) is associated wich each point. The symmetry (or anti-symmetry) type is used to classify the point. The CPCT is especially important in registration applications: the local transformation between interest points can be determined based on their orientational scales. Only points belonging to the same class should be compared. The CPCT detects the features in Mach bands and in sinusoidal waves. This cannot be done by simply looking for local maxima in intensity gradient nor by looking for local energy maxima. I conjecture that constraining the general phase congruency is sufficient for feature detection. The correct detection of features' location and of their scale is demonstrated.