Influence of filter sphericity on the detection of singularities in synthetic images

It has been demonstrated previously that isotropy of wavelets is advantageous for the detection of pointwise singularities. The influence of the isotropy is studied here for a broader class of operators. We compare Gabor filters which provide a relatively high directionality, the spherical wavelet and the Mexican Hat function which is isotropic. From experiments on different backgrounds and with defects of varying size, we observe a clear influence of sphericity on the detection of small singularities.