A density correction unit (a1) obtains density measurement values of a surface in a measurement section of an image carrier at a first round, (a2) calculates as section background data at the first round respective differences between the density measurement values at the first round and an average value thereof, (a3) obtains density measurement values of a surface at least in the measurement section at a second round, (a4) calculates as section background data at the second round respective differences between the density measurement values at the second round and an average value thereof in a specific section with the same length as the measurement section, and (a5) determines the rotation period on the basis of a correlation between the section background data at the first round and at the second round. Here the measurement section is a part in a circulating direction of the image carrier.

An image forming apparatus includes an image former that forms a plurality of adjustment images on a sheet. The plurality of adjustment images are used for adjusting a forming position of a printing image to be formed on the sheet. The plurality of adjustment images are formed at positions that are asymmetrical with respect to the center of the sheet or the center of the printing image.

An image forming apparatus includes an image bearing member, a transfer device, an applying portion; a detecting portion, a controller, and a receiving portion. The controller executes an operation in a setting mode in which during non-image formation, test images are transferred onto the recording material at different test voltages to the transfer device and then a transfer voltage applied to the transfer device during image formation is set on the basis of a detection result of the detecting portion. In a case that the operation in the setting mode is executed to set the transfer voltage for one-side mode, the receiving portion is capable of receiving instruction information selectively instructing a setting condition of the transfer voltage set by the operation in the setting mode from setting conditions including a first setting condition and a second setting condition.

An image forming apparatus includes a platen on which an original is to be placed, a feeder configured to feed an original placed on a tray, a sensor configured to detect a sheet on the tray, a lamp provided to the feeder, a reader configured to read the original placed on the platen and to read the original conveyed by the feeder, an image forming unit configured to form an image on a sheet, and a controller. The controller is configured to control the image forming unit to form a test image on a sheet, control the reader to read the test image formed on the sheet placed on the platen, control a density of the image to be formed by the image forming unit based on a reading result of the test image.

An image forming apparatus includes an image bearing member, a rotatable endless intermediary transfer belt, an inner roller, an outer roller, a power source, a detecting portion, and a controller. On the basis of a result of detection by the detecting portion when a voltage is applied to the inner roller so as to form a chart on a recording material of a predetermined kind in an operation in an adjusting mode, the controller determines whether a transfer voltage when a toner image is transferred onto the recording material of the predetermined kind is subjected to constant-voltage control so that the voltage applied to the inner roller by the power source becomes a target value or is subjected to constant-current control so that a current supplied to the inner roller becomes a target value.

An image-forming apparatus includes a generating unit that generates correction data for correcting an unevenness in light amount of an exposure head using a read image of a correction chart, and a correction unit that corrects image data for image formation based on the correction data. The exposure head includes light-emitting chips, each of which includes light-emitting elements. The correction chart includes a plurality of regions arranged in a direction, a first reference mark located on one side of the regions, and a second reference mark located on the other side of the regions. The generating unit determines partial regions respectively formed by the light-emitting chips within the regions based on positions of the first and second reference marks in the read image of the correction chart, and generates the correction data based on a result of measurement on the partial regions.

An image forming apparatus includes an image forming unit including a photosensitive member, a light source, and a developing roller, and a controller configured to control the image forming unit to form a detection image, obtain density data regarding density levels in a plurality of areas in the detection image at a plurality of positions in a scanning direction in which the photosensitive member is scanned with the light from the light source, generate, based on the density data, a first image forming condition for forming a first test image and a second image forming condition for forming a second test image, the second image forming condition being different from the first image forming condition, and control the image forming unit to form the first test image and the second test image, respectively based on the first image forming condition and the second image forming condition.

An image forming apparatus includes an image processing unit configured to perform image processing corresponding to an image forming mode on image data; a controller configured to control the image processing unit to perform the image processing corresponding to the image forming mode on measurement image data, control an image forming unit to form the measurement image based on the measurement image data, to control a measurement unit to measure the measurement image, and to control an image forming condition based on a measurement result. In a case where the measurement image is formed while the image forming apparatus consecutively forms a plurality of images in the second image forming mode, the controller controls the image forming unit to form the measurement image without performing the image processing corresponding to the second image forming mode.

An image forming apparatus includes a conversion unit, an image bearing member, an image forming unit that forms an image on the image bearing member based on image data converted by the conversion unit, a measuring unit that measures a measurement image on the image bearing member, and a controller that controls the image forming unit to form a first measurement image, controls the measuring unit to measure the first measurement image, and generates a conversion condition based on a result of measurement of the first measurement image and a first feedback condition. In forming a chromatic color image after a predetermined number of monochrome images, the controller controls the image forming unit to form a second measurement image, controls the measuring unit to measure the second measurement image, and generates the conversion condition based on a result of measurement of the second measurement image and a second feedback condition.

An image forming apparatus includes an image forming section; a density detection section configured to detect the density of toner image formed on an image bearing member in a sub scanning direction; and a density-unevenness correction section configured to calculate a first correction amount based on the detection result of the density detection section and calculate a second correction amount different from the first correction amount in phase.