Affine Wigner Moment Invariants

Moments of a Wigner distribution are defined based on both the space and spatial frequency coordinates and are considered as a summarization of the distribution. A method is proposed in this paper to derive functions called affine Wigner moment invariants (AWMI) based on these moments. These functions remain unchanged when the underlying images are affine transformed. As Wigner distributions could be used for texture analysis, AWMI are expected to extract certain texture information. An experiment is reported in this paper to show empirically the functions indeed remain unchanged when the underlying images are affine transformed. And the performance of the AWMI in extracting texture information is compared with that of the affine moment invariants.