1. An image processing apparatus comprising: an interface configured to receive a first image from an external apparatus of a first position and a second image from the external apparatus of a second position, wherein the first image is different from the second image, the first position is different from the second position; and a processor configured to: extract a first character string appearing on the first image, and a second character string appearing on the second image, determine that both the first character string and the second character string correspond to a photographed subject in the first image and second image, cut out each of the characters constituting the first character string, in units of a character, cut out each of the characters constituting the second character string, in units of a character, calculate a first similarity degree group which is composed of similarity degrees between the respective characters constituting the first character string and respective candidate characters in a candidate character group, calculate a second similarity degree group which is composed of similarity degrees between the respective characters constituting the second character string and the respective candidate characters in the candidate character group, and recognize a character string of the subject, based on the first similarity degree group and the second similarity degree group.