US Patent 7298984 Image forming apparatus and developer control method

An image forming apparatus includes a developer that develops a latent image to form an image, a separation unit that separates image information of a job image by color upon writing a latent image of the job image, a comparison unit that compares the image information by color separated by the separation unit with a threshold value previously set with respect to an image concentration, and a driving condition determination unit that determines a driving condition of the developer using a result of comparison by the comparison unit.