Abstract: An image forming apparatus includes an image forming unit configured to form a measurement image on a sheet, a measurement unit configured to radiate light on the measurement image via a transparent window, and measure the light reflected from the measurement image, a white reference plate of which a white level is measured by the measurement unit, a black member of which a black level is measured by the measurement unit, and a determination unit configured to determine, based on a change in a measurement result of the white reference plate and a change in a measurement result of the black member measured by the measurement unit, whether the white reference plate, the black member, or the window is soiled.

Abstract: An image forming apparatus performs control so that a wrinkle is formed at a predetermined position of an intermediate transfer belt and, when forming a toner image having such a large size that the toner image overlaps the wrinkle formed in the intermediate transfer belt, the leading edge and the trailing edge of the toner image overlap the wrinkle.

Abstract: An image forming apparatus performs pseudo gradation processing using dithering, and includes an image carrier; a plurality of light-emitting element arrays arranged in a main-scanning direction and including a plurality of light-emitting elements; an image forming unit performing lighting control of the arrays and forming a pattern image on the image carrier; a detecting unit detecting a density of the pattern image; a position detecting unit detecting a position in the main-scanning direction of the detecting unit with respect to the light-emitting element arrays; a determining unit that, based on the detected position, determines whether the detecting unit is positioned at a proper detection position with respect to the pattern image on which noise has no effect; and an operation control unit that, when the detecting unit is positioned at the proper detection position, performs an image density detection operation on the pattern image using the detecting unit.

Abstract: An image forming apparatus is provided. The image forming apparatus includes: a formation unit configured to form marks for measurement of a positional deviation on a relatively moving object; an optical sensor having a detection region on the object, and configured to output a light receiving signal depending on existence of the marks within the detection region; a removing unit configured to perform a noise removing process, including a first noise removing process and a second noise removing process which use different removing methods for removing noises included in the light receiving signal so as to generate a noise removing result; and a measurement unit configured to measure a positional deviation amount of image formed by the formation unit, based on the noise removing result.

Abstract: An image forming apparatus includes an image forming unit configured to form a toner image on an image bearing member, a first detection unit configured to detect a height of the toner image formed according to a predetermined image forming condition by the image forming unit, a determination unit configured to determine an image forming condition of the image forming unit according to a detection result of the first detection unit, a second detection unit configured to detect a density of the toner image formed according to a predetermined image forming condition by the image forming unit, and a correction unit configured to correct the image forming condition of the image forming unit determined by the determination unit based on the density of the toner image detected by the second detection unit.

Abstract: Provided is a printing apparatus in which a printed material of a same page is printed in almost same color tone even in a case where calibration execution conditions are satisfied in executing printing processing and concentration correction information is updated. A decision portion decides, when a calibration execution portion executes calibration in executing print image data generation processing based on print setting information of N-up printing, poster printing and the like, whether print image data of N-up printing, poster printing and the like is generated using concentration correction information before update or concentration correction information after update based on print setting information analyzed by a data analyzing portion. Then, based on the decision results, the print image data generation portion generates print image data of N-up printing, poster printing and the like.

Abstract: An image forming apparatus includes a developer image forming part, an intermediate transfer body, a primary transfer part, a drive mechanism to drive the intermediate transfer body, a medium carrying mechanism, and a drive controller to control an operation of the medium carrying mechanism. The developer image forming part forms a mark developer image. The developer image detection part detects the mark developer image moving on a carrying path that is from a primary transfer position to a secondary transfer position, and the drive controller controls carrying of a medium based on a detection result of the mark developer image by the developer detection part.

Abstract: An image forming apparatus and an image quality calibration method in the image forming apparatus, the image forming apparatus including a printing unit to print a calibration chart in one mode selected from a plurality of resolution modes, a scanning unit to scan the printed calibration chart, and a calibrating unit to calibrate an image using color values of the scanned calibration chart according to the plurality of resolution modes.

Abstract: A printing apparatus includes an image forming section which forms a toner image of the image to be printed on a recording medium; a transport belt which transports the toner image formed by the image forming section; a light-emitting section which emits a light to the transport belt; a first light-receiving section which is disposed at a position through which a regular reflection light, of the light emitted from the light-emitting section, reflected from the transport belt passes; a second light-receiving section which is disposed at a position different from the position of the first light-receiving section; a transmissive member which is disposed at a position through which the light emitted from the light-emitting section and a reflection light, of the light, reflected from the transport belt pass and which transmits the light and the reflection light.

Abstract: An image forming apparatus for forming a toner image on an image carrier, including: a patch former that forms a solid and a non-solid patch on the image carrier under different image formation conditions; a measurer that measures amounts of toner adhering to the solid and the non-solid patch; a determiner that determines image density properties indicating a relationship between an image formation condition and an amount of adhering toner, based on both (i) a relationship between an image formation condition applied to the solid patch and the amount of toner adhering to the solid patch, and (ii) a relationship between an image formation condition applied to the non-solid patch and the amount of toner adhering to the non-solid patch; and a setter that sets an appropriate image formation condition for forming a toner image having a desired density on the image carrier according to the image density properties.

Abstract: An image forming apparatus includes a toner image forming device that forms a toner image by using at least one of a plurality of toners that include a color toner and a first transparent toner; an intermediate transfer body to which the toner image is transferred; a second transfer unit that transfers the toner image to a recording medium; and a controller that acquires characteristic information that represents a characteristic of in-plane resistance variation of a currently-used recording medium before the toner image forming device forms the toner image, and if the characteristic information indicates that the in-plane resistance variation of the currently-used recording medium is larger than a predetermined value, controls the toner image forming device so that the toner image forming device forms a transparent toner image in such a way that a color toner image is superimposed on the transparent toner image on the intermediate transfer body.

Abstract: Provided is a detecting apparatus including an illumination optical system for emitting an image bearing member with a light beam emitted from a light source unit, an imaging optical system including an imaging optical element for imaging an image on the surface of the image bearing member, a light receiving unit for detecting the image on the image bearing member which has been imaged by the imaging optical system, and a calculation unit for detecting image information on the image on the image bearing member from a detection signal received from the light receiving unit. In the detecting apparatus, at least one optical plane of the imaging optical element is configured to refract an imaging system principal ray after passing therethrough in a direction of farther becoming apart from the light source unit than the imaging system principal ray before passing through the optical plane.

Abstract: An image forming apparatus includes a transport member that transports a recording medium, an image carrier that carries a toner image, a transfer member that transfers the toner image onto the recording medium, a fixing device that fixes the toner image, a reversing path that reverses the recording medium, and a controller. When the toner image is a borderless image and there is a burr on an edge portion of the recording medium, the controller controls the transport member, the image carrier, and the transfer member so that the recording medium passes between the image carrier and the transfer member and through the fixing device without the toner image being transferred onto the recording medium, and then the recording medium is transported along the reversing path to between the image carrier and the transfer member and the toner image is transferred onto the recording medium.

Abstract: An image forming apparatus comprises: an image forming unit configured to form an image quality adjustment pattern image on an image carrier to be driven at a predetermined speed; a detector configured to detect the image quality adjustment pattern image; an image quality adjustment controller configured to control image quality adjustment processing in accordance with a detection result by the detector; a speed change unit configured to change an image formation speed indicating a speed at which an image is formed, and an interval change unit configured to change an interval at which the detector acquires a detection result in accordance with a change amount between the image formation speed before changed by the speed change unit and the image formation speed after changed.

Abstract: Disclosed is an image processing device including: a sample output unit to instruct a print device to successively print test images on a plurality of sheets of the recording paper; a profile preparing unit to prepare a plurality of profiles of the density unevenness in the sub-scanning direction in the plurality of sheets of the recording paper, from measuring data obtained by optically reading the test images; an analyzing unit to analyze the profiles by arranging the profiles in a printing order apart from each other so as to correspond to intervals of the sheets of the recording paper, and to detect a long period density unevenness in the sub-scanning direction, which has a long period extending through the plurality of sheets of the recording paper; and a correction data preparing unit to prepare correction data for removing the long period density unevenness.

Abstract: This invention is to provide a technique of always obtaining a stable output image in image formation using toner. A supplier (1217) supplies toner in a decided toner supply amount. A developing device (1206) agitates the supplied toner and supplies the agitated toner to an electrostatic latent image formed on a photosensitive drum (1203), thereby developing a toner image on the photosensitive drum (1203). A correction amount calculation unit (1106) estimates the toner charge amount by calculating a function model that approximates the variation characteristic of the toner charge amount using the toner consumption necessary for printing a print target image, the toner supply amount necessary for printing the print target image, and the toner agitation time. At least one of an image processing condition and a process condition is controlled using the estimated toner charge amount.

Abstract: A method of controlling a color-tone density (CTD) of an image forming apparatus including a plurality of developers configured to circularly perform a developing operation. The method includes developing test patches on an OPC sequentially from a developer to be developable preferentially, measuring CTDs of the developed test patches, and controlling a development variable using the measure CTDs.

Abstract: An image forming system is provided. The image forming system includes an image forming apparatus configured to form a mark for detecting at least one of a position deviation and a density deviation and obtains a correction amount by detecting the mark, the image forming system comprising: an identification unit configured to identify an image characteristic of an image to be printed according to at least one of a positional relationship between colors, a gradation distribution and a resolution, and a selecting unit configured to select a choice from multiple choices containing at least two choices of: only position deviation; only density deviation; and both position deviation and density deviation, according to the image characteristic identified by the identification unit, wherein the image forming apparatus is configured to form the mark for obtaining the correction amount according to the choice selected by the selecting unit.

Abstract: A toner pattern for detecting the degree of toner deterioration is created on a photosensitive element and transferred to an intermediate transfer belt by a primary transfer unit under a transfer condition different from that at the time of image formation. A toner adhesion amount detection unit detects the toner adhesion amount of the toner pattern at multiple places. A degree-of-toner-deterioration calculation unit calculates the degree of toner deterioration on the basis of the variation in data of the toner adhesion amount at multiple places detected by the toner adhesion amount detection unit. A background potential determination coefficient in a process control unit is controlled on the basis of the degree of toner deterioration calculated by the degree-of-toner-deterioration calculation unit.

Abstract: In a reflective optical sensor in an image forming apparatus, an output from each N number of light-receiving elements (N?3), obtained when M number of light-emitting elements (M?3) included in a light-emitting unit emit detecting light, is separated into an amount of specularly reflected light and an amount of diffusely reflected light. The toner density of a pattern, which is formed on a supporting member in the image forming apparatus, is calculated based on a sum of the amounts of specularly reflected light and a sum of the amounts of diffusely reflected light.

Abstract: A toner image for measurement of an area coverage modulation of 90% or more is formed on a photosensitive drum in a non-image formation, and a setting condition for defining a developability of a toner image in an image formation is set so that a detection result of an optical sensor detecting the toner image for measurement becomes a preset target value. The target value is set to be lower as a value of the setting condition increases from a lower side to a higher side of the developability. The target value is set so that a color difference ?E of an image having half the maximum image density obtained after the setting condition is set with respect to an image having half the maximum image density obtained after the setting condition is set in a setting mode with use of unused developer is 6.5 or less.

Abstract: The image forming apparatus includes process units that are closely arranged around respective photosensitive members and act on the photosensitive members, a light emission section that forms an electrostatic latent image for detection on the photosensitive member and a detection section that detects that the electrostatic latent image passes through a position facing the process unit, and a control section that performs misregistration correction control based on the detection result.

Abstract: An image forming apparatus includes: a belt; a plurality of photosensitive units that contact the belt are disposed at a predetermined interval in the transportation direction of the belt and transfer marks for image adjustment to the belt, images of different colors being respectively formed on the plurality of photosensitive units; an exposure unit that exposes the photosensitive units by light so that the marks are disposed at the same interval on the belt; a detector that detects the marks transferred to the belt; and an image adjustment unit that performs an image adjustment based on a detection result of the detector. A width and an interval of the marks in the transportation direction are set so that a mark of at least one color does not exist in all contact areas of the belt contacting the plurality of photosensitive units.

Abstract: An image forming apparatus uses the difference in time taken for each patch to reach a color sensor, which occurs upon reversing the conveyance direction of a printing material. Due to this difference in time, the temperature of the printing material in detection by the color sensor differs among the respective patches. The error of a colorimetric value due to thermochromism is reduced by placing a patch with a colorimetric value which has a low temperature dependence so as to be detected earlier, and a patch with a colorimetric value which has a high temperature dependence so as to be detected later.

Abstract: Embodiments described herein include a multi-color printing system in which color-to-color registration errors due to cyclical belt motion errors are minimized. A belt for transporting a substrate media or at least a partial image into a plurality of panels is segmented. A first one of the panels has a first location on the belt for receiving substrate media or a partial image. A first belt motion error value corresponding to the first one of the panels on the belt is identified and at least one image marking unit is calibrated to counteract the first belt motion error corresponding to the first one of the panels.

Abstract: An image control apparatus according to an embodiment includes: a traveling member which carries a toner image; a detection unit which detects an adjustment pattern formed on the traveling member; and a control unit which generates an edge detection signal obtained by binarizing a detection result from the detection unit, and generates converted data obtained by analog-digital converting the detection result from the detection unit.

Abstract: An image processing apparatus includes an image forming unit, an adjustment unit, an image control unit, a sensor, a deviation amount calculating unit, and a determination unit. The image forming unit forms an image. The adjustment unit forms one set of a plurality of predetermined images in color, and adjusts color deviation. The image control unit controls the image forming unit to form a lesser number of predetermined images than the number of predetermined images formed by the adjustment unit. The sensor detects the predetermined images formed on the basis of control of the image control unit by the image forming unit. The deviation amount calculating unit calculates a deviation amount on the basis of the predetermined images. The determination unit determines whether or not color deviation occurs on the basis of the deviation amount, and controls performance of the adjustment unit on the basis of the determination result.

Abstract: An image forming apparatus includes a control unit configured to detect a misregistration amount and densities of the toner images by detecting first and second detection patterns. The first detection pattern includes black and color portions, and the control unit is further configured to set a light-emitting amount of a detection unit, a threshold, or a sensitivity of a detection unit so that a received light amount of diffuse reflection light from the black portion is less than the threshold and a received light amount of diffuse reflection light from the color portion exceeds the threshold, and to set the light-emitting amount or the sensitivity so that the received light amount of the diffuse reflection light from the color portion is less than an upper limit of the detection unit.

Abstract: An image forming apparatus includes: image forming unit configured to form a density detection pattern and a reference pattern on an image carrier by a developer; a light-receiving unit configured to receive reflection light of light emitted toward the image carrier, and output a signal corresponding to an amount of received light; a sampling unit configured to sample the signal output from the light-receiving unit, and store sampling values in the storage unit; a detection unit configured to detect the reference pattern; and a determination unit configured to determine a sampling value corresponding to reflection light from the density detection pattern of the color among the sampling values stored in the storage unit, based on a detection time of the reference pattern.

Abstract: An image forming apparatus includes: a forming unit configured to continuously form, on an image carrier, a first and second detection patterns for detecting relative registration amounts and a density of each of a plurality of colors; and a control unit configured to control registration and the density. The forming unit forms the detection patterns such that a leading edge developer color of a detection pattern formed on a front side among the two detection patterns, in a direction in which the detection patterns are moved by rotation of the image carrier, is the same as a trailing edge developer color of the detection pattern formed on the front side, or a leading or trailing edge developer color of a detection pattern formed on a rear side among the two detection patterns.

Abstract: An image forming apparatus includes: an image forming unit configured to form, on an image carrier, a first correction pattern including developer images of a plurality of colors, and a second correction pattern including developer images of the plurality of colors; a registration correction unit configured to perform registration correction control based on a detection result of the developer images of the first correction pattern; and a density correction unit configured to perform density correction control based on a detection result of the second correction pattern. The density correction unit is further configured to decide a detection result of the developer image of at least one color of the second correction pattern used for the density correction control based on a detection result of the developer image of the first correction pattern.

Abstract: An image forming apparatus includes: a density detection unit that detects densities of an image developed by a developing unit at a plurality of positions in a main-scanning direction; a processing unit that obtains at least one of an amplitude and a phase of a first periodical density change of the image, of which cycle is a rotation cycle of a photosensitive drum, at the plurality of positions in the main-scanning direction on the basis of an output signal of the density detection unit, and corrects a drive signal for the light source so as to suppress the first periodical density change of the image at each position in the main-scanning direction on the basis of the rotation cycle of the photosensitive drum and at least one of the amplitude and the phase.

Abstract: An image forming apparatus is provided. The image forming apparatus includes: a forming unit configured to form an image on a relatively moving object, the image including a mark; a first detection unit configured to detect the mark formed by the forming unit so as to obtain a first detection result; a correction unit configured to execute a correction process in which an image forming condition of the image forming unit is changed based on the first detection result; a setting unit configured to set the correction process not to be executed when a value related to a correction accuracy of the correction unit is lower than a reference value; and a control unit configured to control the correction process based on the setting by the setting unit.

Abstract: An image forming apparatus includes a photosensitive member; a charging device for electrically charging the photosensitive member; an exposure device for exposing to light the photosensitive member electrically charged by the charging device to form an electrostatic image; a developing device for developing the electrostatic image with toner to form a first patch and a second patch; a detecting device for detecting a density of the first and second patches formed by the developing device; and a control device for controlling an image forming condition on the basis of a difference in density between the first patch formed on the photosensitive member at a portion where a surface potential of the photosensitive member is zero volts and the second patch formed at a portion electrically charged by applying a predetermined charging bias to the charging device.

Abstract: An image forming system including a first image forming apparatus and a second image forming apparatus. The first image forming apparatus forms an image on a first side of a recording medium and has a mark forming device to form a mark on the recording medium. The second image forming apparatus forms an image on a second side which is the obverse of the first side, and has a mark detector to detect the mark at a predetermined position in a conveyance path of the recording medium and a calculator to calculate an expansion and contraction ratio of the recording medium in a first direction and in a second direction perpendicular to the first direction based on the output of the mark detector.

Abstract: An image forming apparatus is provided. The image forming apparatus includes: a manual acquiring unit which is configured to receive a user input to acquire a correction value; an image forming unit which is configured to form an image while adjusting at least one of positional deviation and density deviation of the image based on the correction value; and a changing unit which is configured to execute at least one of a first changing process of changing a permissible range of a correction value for positional deviation according to a status of a factor causing a change in a position of an image, and a second changing process of changing a permissible range of a correction value for density deviation according to a status of a factor causing a change in a density of an image.

Abstract: A computer-based apparatus for preventive maintenance detection for a color printer including a photoreceptor belt (PB) arranged to displace in a process direction, including a memory element for storing a threshold value, computer readable instructions, and registration data for a plurality of markings on a surface of the PB, including for each marking, a respective registration difference, in a lateral direction orthogonal to the process direction, between a respective actual location and a respective original location. The apparatus includes a processor configured to execute the computer readable instructions to: determine that at least one marking from the plurality of markings is out of compliance with the at least one threshold value; and in response to determining that at least one marking from the plurality of markings is out of compliance with the at least one threshold value, transmit a signal, indicating that maintenance is required for the PB, for display.

Abstract: A fixing device includes a fixing unit, a shearing unit, a detection unit, and a controller. The fixing unit fixes a toner image in place on a printed surface of a recording medium. The shearing unit is disposed downstream from the fixing unit along the media conveyance path to at least partially shear toner from the fixed toner image, so as to create a shorn image area that exhibits a different image density than that of an intact, unshorn image area on the printed surface of the recording medium. The detection unit is disposed at least partially downstream from the shearing unit along the media conveyance path to measure the image densities of the shorn and unshorn image areas. The controller is operatively connected to the fixing unit and the detection unit to adjust one or more operational parameters according to a difference between the measured image densities.

Abstract: An image forming apparatus of the present invention includes an endless belt that travels circularly by a drive member and has an outer peripheral surface on which an image is formed; a tension applying member around which the endless belt is trained and that applies tension to the endless belt by pressing an inner peripheral surface of the endless belt; a detection member that detects the image formed on the outer peripheral surface of the endless belt; a support member to which the detection member is attached and that movably supports the detection member with respect to an apparatus main body; and a positioning member that positions the detection member with respect to the outer peripheral surface of the endless belt at a portion pressed by the tension applying member.

Abstract: When a toner image formed on the surface of a photosensitive drum is transferred onto an intermediate transfer belt, a transfer bias is applied to a primary transfer portion. When a patch formed in an upstream image forming station and transferred onto the intermediate transfer belt and a patch formed on the surface of the photosensitive drum pass through the primary transfer portion, a passing bias different from the transfer bias is applied to the primary transfer portion. A control section controls a laser beam scanner as exposure member not to expose the surface of the photosensitive drum to which the passing bias is applied.

Abstract: An image forming apparatus having an improvement to increase the reliability of a sensing operation that is carried out to improve image quality, and a transfer device thereof. The image forming apparatus includes at least one photosensitive member, a plurality of developing units to supply developer to the at least one photosensitive member so as to form a visible image, and a transfer belt to transfer the visible image formed on the at least one photosensitive member to a printing medium, an inner surface of the transfer belt being rotatably supported by at least two rollers. The image forming apparatus further includes at least one sensor to sense a mark formed on the transfer belt, and a supporting unit to support the transfer belt at a position corresponding to the at least one sensor so as to apply a tensile force to the transfer belt.

Abstract: An image output device includes a storage unit, an input unit, a layout deriving unit, and an output unit. The storage unit preliminarily stores therein an optimum interval of a plurality of the same color and tone patches formed on a sheet at which an average density value of the patches is stabilized. The input unit receives an input of a condition for arrangement of the patches from a user. The layout deriving unit determines arrangement of the patches on the sheet on the basis of the input condition for arrangement and the optimum interval. The output unit outputs the patches onto the sheet in the determined arrangement.

Abstract: There is provided an image forming apparatus which shortens the time taken for circumference detection and measures the circumference at high precision without obstructing downsizing of the apparatus. To accomplish this, the image forming apparatus detects, at an arbitrary timing, the physical pattern of the image-formed surface of a rotation member that changes over time. In the second round, the image forming apparatus detects the second pattern at a timing a predetermined time after the arbitrary timing. By using the detected patterns, the image forming apparatus obtains information associated with the circumference of the rotation member.

Abstract: An image processor includes an identifying unit, a first correcting unit, and a second correcting unit. The identifying unit identifies a white point value of an image represented by first image data. The white point value indicates a first color temperature. The first correcting unit performs a white balance correction on the first image data such that the white point value approaches a target white point value. The target white point value indicates a second color temperature. The second correcting unit performs a brightness correction for correcting the first image data corrected by the first correcting unit into second image data such that an image corresponding to the second image data is brighter as the second color temperature is higher than the first color temperature and such that the image corresponding to the second image data is darker as the second color temperature is lower than the first color temperature.

Abstract: Non-uniformity of a rotatable electrophotographic imaging component is compensated. The component has an intentional periodic variation that produces density variations in a test target. The angular position on the component of the intentional variation is correlated with the amount of an unintentional variation at several points to produce a non-uniformity map. An image signal with multiple regions of data is received. For each region, the angular position of the intentional variation in that region is determined, and the non-uniformity map is used to determine the correction required for the unintentional variation. The image data in the region are adjusted to compensate, and corresponding toner is deposited.

Abstract: An image forming apparatus includes an image forming unit configured to form a toner image on an image bearing member, a first detection unit configured to detect a height of the toner image formed according to a predetermined image forming condition by the image forming unit, a determination unit configured to determine an image forming condition of the image forming unit according to a detection result of the first detection unit, a second detection unit configured to detect a density of the toner image formed according to a predetermined image forming condition by the image forming unit, and a correction unit configured to correct the image forming condition of the image forming unit determined by the determination unit based on the density of the toner image detected by the second detection unit.

Abstract: Methods are provided for automatic cross-track density correction for a print engine having a print head that forms lines of picture elements on a receiver based upon lines of pixel values. In one aspect of the method, the print engine is caused to print a first print having a plurality of different areas along a cross-track direction with target densities and data is received from which measured densities for different ones of the plurality of different areas can be determined. A line density adjustment function is based upon a functional relationship between a cross track position of different ones of the areas and a difference between the measured density and the target density at the different ones of the areas. A production print is subsequently printed according to lines of pixel values for the production print modulated by the line density adjustment function.

Abstract: A method and system for printing image documents using a variety of toners where some toners using a multi-development station having two or more development stations. These toners are co-printed prior to fixing, on the receiver by the multi-development station.

Abstract: A colorimetric chart, for measuring a color reproduction characteristic of an image forming apparatus, includes: a patch column that is arranged in a sub-scanning direction representing a conveying direction in which the image forming apparatus conveys the colorimetric chart and that is used in detecting periodic color fluctuation attributed to the image forming apparatus, wherein the patch column includes patches that are arranged in different phases on the same patch column.

Abstract: An image forming apparatus which reduces downtime by starting image density detection without waiting for identification of the same position on a rotary member. A detection unit detects a surface condition of a rotary member on which a toner image on a photosensitive drum is transferred. An identifying unit matches first data detected by the detection unit on a reference point on the surface of the rotary member and second data detected by the detection unit after obtainment of the first data to identify the reference point. A control unit controls image density based on a detection result obtained by the detection unit on a base of the rotary member corresponding to a range where a measurement image is formed and an obtained detection result on the measurement image by referring to the reference point identified as a reference.