1. A method, comprising: a computing system receiving a first training image; the computing system determining a plurality of pixel neighborhoods in a second training image that is a lower-resolution version of the first training image, wherein the plurality of determined pixel neighborhoods have a number of distinct pixel arrangements in the second training image, and wherein at least two of the plurality of pixel neighborhoods have identical pixel arrangements in the second training image; the computing system determining, for each of the distinct pixel arrangements in the second training image, a corresponding pixel value in the first training image; and for each of the identical pixel arrangements in the second training image having a plurality of corresponding pixel values in the first training image, the computing system calculating a single corresponding pixel value based on the plurality of corresponding pixel values in the first training image.