1. An image processing apparatus comprising: a recognition unit that recognizes a layout of a line including a character string in an image read from an original; a determination unit that determines a size of a region in which additional information is embedded so as to include at least a part of a line including a character string in the region, based on the layout recognized by the recognition unit; a dividing unit that divides the image read from the original based on the size of the region determined by the determination unit; and an embedding unit that embeds the additional information in the image divided by the dividing unit.