2, the size of the photo is different at home and abroad, the domestic name is 5 inches, 6 inches, 7 inches ..., and the numerical value is the long side of the photo; The international names are 3R, 4R and 5r, and the values are taken from the shorter side of the photo.
Extended data:
R stands for Rectangle (English is rectangle), calculated with the shortest side; For example, 3R means "3.5 inches by 5 inches".
S stands for square (English for square); For example, 3S means "3 inches by 3 inches".
1 inch =2.54 cm. When we talk about the size of a photo, we usually talk about inches (referring to the long side of the photo). The general standard of photo size is 2 within 10 inch. For example, a 5-inch photo is 5x3. 7 inches = 7× 5; 8 inches =8×6 inches. If the photo size is greater than 10 inch, the difference is 4 12 inch =12× 8; 14 inch =14×10; 18 inch =18×14; And so on.