Patent ID: 8305644

Claim:
An image forming device comprising: at least one processor programmed to control: a storing unit configured to maintain density-correction-table lists generated by forming patch images which are different from one another in density on a photosensitive drum after printing data having a first image ratio on a predetermined number of sheets, reading the formed patch images by a sensor, obtaining, from density values of the read patch images, amounts of density changes that exist after printing the data having the first image ratio on the predetermined number of sheets, forming patch images which are different from one another in density on the photosensitive drum after printing data having a second image ratio on a predetermined number of sheets, reading the formed patch images by the sensor, and obtaining, from density values of the read patch images, amounts of density changes that exist after printing the data having the second image ratio on the predetermined number of sheets; a counter unit configured to execute a printing job to start a printing process and count up a number of printed sheets; a calculation unit configured to calculate, when the number of printed sheets counted by the counter unit achieves a predetermined number, an image ratio used for printing the predetermined number of sheets; an obtaining unit configured to obtain from the maintained density correction table lists and with reference to the amounts of density changes on the maintained density correction table lists, each amount of density changes occurred since the start of the printing job, in accordance with the calculated image ratio and the counted number of printed sheets; and a density correction unit configured to correct a density of image data generated from a print job which, among the printing jobs, is not yet executed, by using the obtained amounts of density changes.