1. A computer-implemented method comprising: obtaining a first image of an eye, wherein the first image includes a view of a portion of a vasculature of the eye external to a corneal limbus boundary of the eye; determining a plurality of metrics for the first image, wherein the metrics include a first metric for reflecting an extent of one or more connected structures in the first image that represents a morphology of eye vasculature and a second metric for comparing an extent of eye vasculature detected across different color components in the first image, where determining the second metric comprises: determining a first color difference signal by subtracting a first color component of the first image from a second color component of the first image, determining a second color difference signal by subtracting a third color component of the first image from the first color component of the first image, and determining a ratio of a first standard deviation of the first color difference signal to a second standard deviation of the second color difference signal; determining a quality score based on, at least, the plurality of metrics for the first image, wherein the quality score is a prediction of a match score that would be determined based on the first image and a second image, assuming the first image and the second image included a view of the same person's vasculature; and rejecting or accepting the first image based on the quality score.