The printing apparatus comprises: a unit configured to print a plurality of color planes corresponding to the image in an overlapping manner at the formation position indicated by the detected first mark and print a plurality of second marks corresponding to each of the plurality of color planes on the continuous sheet; and a unit configured to adjust printing start timing of the color plane so as resolve a shift in each of the color planes based on detection results of the plurality of second marks. Then, the plurality of second marks is printed at an end portion of the continuous sheet so that at least part of the plurality of second marks overlaps the first mark in the sheet width direction.

In an image forming apparatus, a length of a patch pattern from a first patch to a last patch included in the patch pattern is longer than a circumferential length that is a length of an intermediate transfer belt in a conveyance direction, an engine control unit forms patches included in a range within the circumferential length in a first density (low density), forms patches included in ranges beyond the circumferential length in a second density (high density) darker than the first density, from among the patches included in the patch pattern, and executes image adjustment control.

An image forming apparatus receives light from an intermediate transfer member or a correction pattern. The pattern includes an overlapping pattern on which a first monochromatic toner image is formed as a lower layer and a second monochromatic toner image having a smaller area than the first monochromatic toner image is formed as an upper layer. The image forming apparatus controls a plurality of image forming units to form the overlapping pattern such that a dynamic range becomes less than 1.0 and greater than 0.5.

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 first test image on a sheet, control the reader to read the first 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 first test image.

An image forming apparatus that includes an imaging device, a transferrer, a rotator, a rotation position sensor, an adhesion amount sensor, a power supply, and a controller. The controller executes a construction process to construct output pattern data to change a voltage output from the power supply, according to a result obtained by detecting a toner adhesion amount of a toner image for density unevenness detection and a detection result from the rotation position sensor obtained when the toner image is formed, and an output change process to execute a predetermined process while changing the voltage according to the detection result and the output pattern data. The controller executes a determination process to determine propriety of an output range of the voltage output from the power supply by the output change process and a data process for a shift to shift the range when a determination result is inappropriate.

An image forming apparatus includes: an image forming unit including a rotating member and being configured to form an image on a paper sheet in accordance with print job data; a rotation position detecting unit configured to detect a rotation position of the rotating member; an image density detecting unit configured to detect a density in an image formed on an image carrier; an image information analyzing unit configured to analyze image information in the print job data; a density profile managing unit configured to form a correction patch image on the image carrier, and create and manage a density profile indicating periodical density unevenness; a correction data creating unit configured to create correction data; a density correcting unit configured to perform density correction; and a density correction control unit configured to predict an appearance of periodical density unevenness, and set conditions for the density correction.

An image forming apparatus includes a rotatable image bearer, a toner image forming device, an image reader, and a control unit. The toner image forming device forms a test toner image on the image bearer. The image reader reads the test toner image and a predetermined reference member. The control unit calculates an amount of toner contained in the test toner image based on image data from the test toner image. Based on image data from the reference member, the control unit selects a position of a pixel to be used for calculation of the amount of toner contained in the test toner image from pixels included in the image data from the reference member, to calculate the amount of toner contained in the test toner image from data of a pixel located at the position thus selected among pixels included in the image data from the test toner image.

An image forming apparatus forms a measurement image, controls a sensor to measure light reflected from a first area of an intermediate transfer member, controls the sensor to measure light reflected from a measurement image, and controls the sensor to measure light reflected from a second area of the intermediate transfer member. The apparatus determines first information relating to a tendency of the measurement results of the first area, determines second information relating to a tendency of the measurement results of the second area, and selects a computational equation for computing a correction value of a measurement result of the measurement image. The apparatus generates a correction value. The apparatus adjusts an image forming condition.

An image forming apparatus includes a detection unit configured to detect a test pattern formed on an image carrier by image forming units; and an adjustment unit configured to control the image forming units to form the test pattern, and adjust relative positions of images based on a detection result of the test pattern. The adjustment unit is further configured to control the image forming units to form the test pattern after the image forming units have formed on the image carrier an image to be transferred to a sheet with a basis weight less than a threshold, and before the image forming units form on the image carrier an image to be transferred to a sheet with a basis weight greater than the threshold.

An image forming apparatus includes an image forming section, a transferred member, a transfer roller, and a separator. The image forming section forms a developer image. The transferred member is conveyed in a first direction and the developer image is to be transferred on the transferred member. The transfer roller faces the transferred member, and makes a transition between a biasing state in which the transferred member is biased by the transfer roller and a separated state in which the transfer roller is separated away from the transferred member. The separator starts to separate a medium away from the transferred member after the transfer roller starts making a transition from the biasing state to the separated state, the medium being held between the transferred member and the transfer roller in the biasing state.