1. An image processing apparatus comprising: a print control unit configured to cause a printing apparatus to print, on a sheet, an image stored in a memory, such that the image is printed on the sheet with a density lower than a predetermined density value; an acquiring unit configured to acquire a read image obtained by reading, by a reading apparatus, the sheet corresponding to the image printed by the print control unit on the sheet; an extracting unit configured to extract information that is added by a user on the image printed by the print control unit on the sheet, from the read image acquired by the acquiring unit, based on the read image; and a combining unit configured to combine the image stored in the memory and the information extracted by the extracting unit, wherein the extracting unit specifies the information from the read image, according to a level of each of a plurality of color components included in the read image, and extracts the specified information from the read image.