In order to detect vessels at a variety of widths, we apply the matched filter at multiple scales (i.e., compute for multiple values and then combine the responses across scales). Unfortunately, the output amplitudes of spatial operators such as derivatives or matched filters generally decrease with increasing scale. To compensate for this effect, Lindeberg introduced gamma-normalized derivatives. We use this notion to define a gamma-normalized matched filter,
['Michal Sofka', 'Charles V. Stewart']
Erratum to “Retinal vessel centerline extraction using multiscale matched filters, confidence and edge measures”