An image forming apparatus includes a reading unit that reads image data, a drawing data storage unit that stores object data comprising the read image data so as to allow the stored object data to be distinguished between a vector object and a raster object, a vector gray determination unit that determines whether each of stored vector objects is formed of an achromatic color, a raster gray determination unit that determines whether each of stored raster objects is formed of an achromatic color, and an output data creation unit that converts the stored object data into multicolor when the stored object data includes a chromatic color and converts the stored object data into monochrome when the stored object data is formed only of achromatic colors.