A homography is determined between a test image and a plurality of database images based on a location of a character along a main line of text of the test image. A similarity score is determined for each of the plurality of database images based on the determined homography. The similarity score may measure a similarity of a characteristic between the test image and the corresponding database image. The characteristic may be at a location separate from the main line of text of the test image. A type of the test image may be selected based on the similarity scores.