Pattern recognition by means of the Radon transform and the continuous wavelet transform

Abstract It is known that the detection of segments in digital pictures can be effectively performed by means of the Radon transform (RT), which concentrates the information about linear features of an image in few high-valued coefficients (i.e. peaks) in the transformed domain. We describe a post-processing method based on the continuous wavelet transform (CWT), which provides information to be used in the recognition task by means of the analysis of the wave shapes of these peaks. We show that this RT- and CWT-based technique can also be successfully applied to the detection of rectangular shaped objects without modifications, and is able to provide information on their width; a further generalization is described in the case of the detection of spots of circular and square shape. Several applications can be devised in the field of land and sea monitoring. A case of interest occurs in aerial images of sea regions, when such patterns, suitably combined, can be thought of as ‘V’-shaped wakes of sailing ships plus, in case, the ships themselves; a technique for the detection of such objects is proposed through an example of application.