1. A computer implemented method comprising: obtaining one or more first image regions of a first image of an eye, wherein each of the first image regions includes a view of a respective portion of vasculature of the eye; training a classifier using a training algorithm and descriptors derived from filters applied to eye images; determining a confidence threshold of the trained classifier based on a false reject or a false accept point of a receiver operating characteristic curve generated from a sensitivity analysis of the classifier; and until a score exceeds the confidence threshold, progressively increasing a filter resolution and calculating the score based on the filter resolution as follows: applying a plurality of filters having the filter resolution to the first image regions to generate filter output; deriving a plurality of first descriptors from the filter output; defining a plurality of second descriptors derived from second image regions of a second image of an eye, the second image regions comprising regions that are co-registered with the first image regions for corresponding descriptors in the plurality of first descriptors; and providing the first descriptors and at least a subset of the second descriptors as input to the classifier and obtaining the score as output of the classifier.