1. A computer-implemented method, comprising: obtaining a first image from a database, the first image associated with a first database entry; obtaining a second image from a database, the second image associated with a second database entry; determining, using a computing system, a similarity between the first image and the second image; and when the first image is determined to be similar to the second image, altering the second database entry in the database, wherein determining the similarity between the first image and the second image includes: determining a plurality of first set intensity vectors for the first image, each of the plurality of first set intensity vectors corresponding to a different one of a plurality of first set pixels of the first image; determining a plurality of second set intensity vectors for the second image, each of the plurality of second set intensity vectors corresponding to a different one of a plurality of second set pixels of the second image, the plurality of the second set pixels corresponding to the plurality of the first set pixels; determining a plurality of first random intensity vectors for the first image, each of the plurality of first random intensity vectors corresponding to a different one of a plurality of first random pixels of the first image that are selected randomly in the first image; and determining a plurality of second random intensity vectors for the second image, each of the plurality of second random intensity vectors corresponding to a different one of a plurality of second random pixels of the second image, the plurality of second random pixels selected based on and corresponding to the plurality of first random pixels, wherein the similarity between the first image and the second image is determined based on the plurality of first set intensity vectors, the plurality of second set intensity vectors, the plurality of first random intensity vectors, and the plurality of second random intensity vectors.