20.32cm×15.24cm is the size of an eight-inch photo. The size of a photo is usually measured in inches, with 1 inch being approximately equal to 2.54 centimeters. An X-inch photo refers to a photo with one side measuring X inches. For example, a 5-inch photo has a length of 2.54×5=12.7cm, and a 12-inch photo has a length of 2.54×12=30.5cm. Identification cards, medical examination forms, and others often adopt a small size, such as one inch which measures 22×32mm. The second-generation ID card photo has dimensions of 26mm×32mm, while a regular one-inch photo is 25mm×35mm.

Digital Photos: Photos taken with a digital camera usually have a 4:3 aspect ratio (consistent with the ratio of our displays), while enlargements of photos typically have an aspect ratio of around 3:2 (consistent with the aspect ratio of film negatives). Therefore, when enlarging digital camera photos, it is generally necessary to crop the photo to a 3:2 aspect ratio so that the enlargement can fully cover the entire photo paper.