An image forming apparatus improves precision in adjudicating the type of the recording medium while also minimizing the time required to make such an adjudication. To accomplish this, the apparatus includes a storage unit that stores a plurality of types of particular shape images that configures a two-dimensional bar code. The apparatus forms a measurement pattern image for measurement, which includes one or more of the particular shape images, upon an image carrier and reads in the measurement pattern image that is formed upon the image carrier. The apparatus then determines a difference between a shape of the particular shape image that is included in the measurement pattern image and a shape of the particular shape image that is stored in the storage unit and subsequently determines an image forming condition with regard to the particular shape image stored in the storage unit.