1. A compact apparatus for iris image acquisition, the apparatus comprising: a sensor for acquiring an infra-red image of a subject's iris and a non-infra-red image of a feature of the subject; and a filter array for selectively filtering light to the sensor, the filter array comprising a plurality of infra-red cut regions for sampling non-infra-red data for the non-infra-red image, and a plurality of infra-red pass regions for sampling infra-red data for the infra-red image.