1. An image processing apparatus comprising: a separation unit adapted to determine an attribute of data contained in input document image data and separating the document image data into areas by attributes; an extraction unit adapted to extract, from the separated areas, an area of a graphics image as a target of vectorization processing; a determination unit adapted to determine whether an attribute of the area of the graphics image is a clipart area or a line drawing area including a line drawing; and a vector conversion unit adapted to perform vectorization processing corresponding to the attribute of the graphics image based on a determination result of said determination unit.