1. An image processing device comprising: an image sensor for acquiring an image depicting one or more face regions; and a processing module configured to: select, from said one or more face regions, a particular face region that includes one or more eye-iris regions; analyze the one or more eye-iris regions to select a particular eye-iris region that comprises a particular eye-iris pattern, which allows to biometrically identify a person depicted in said image; submit one or more eye-iris patterns, from the one or more eye-iris regions, to a biometric authentication unit (BAU); for the particular eye-iris pattern, from the one or more eye-iris patterns: receive, from the BAU, a BAU generated eye-iris code confirming that the particular eye-iris pattern is of a quality insufficient to biometrically identify an individual; adjust a contrast of the particular eye-iris pattern; and in response to adjusting the contrast of the particular eye-iris pattern, re-submit the adjusted particular eye-iris pattern to the BAU for confirming that the adjusted particular eye-iris pattern is of a quality sufficient to biometrically identify the individual; generate a substitute eye-iris region comprising a substitute eye-iris pattern that is distinct from the particular eye-iris pattern included in the particular eye-iris region; wherein the substitute eye-iris pattern does not allow to biometrically identify said person; replace, in the particular face region, the particular eye-iris region with the substitute eye-iris region; and store, in a storage device, said image, which includes the substitute eye-iris region in the particular face region.