1. A method to identify items depicted in an input image, the method comprising: comparing, with a processor, a first image signature associated with the input image with a plurality of reference signatures associated with a plurality of reference images to identify a first reference image matching the input image; identifying, with the processor, a first group of items depicted in the input image as corresponding to a first group of reference items registered with the first reference image; determining, with the processor, that a first region of the input image differs from a corresponding first region of the first reference image; and in response to determining that the first region of the input image differs from the corresponding first region of the first reference image, processing, with the processor, the first region of the input image based on a template to identify a second item depicted in the first region of the input image.