An optical sensor includes a first light emitting diode (LED), a second LED, a first photodiode (PD), and a second PD. The first LED and the second LED are configured to irradiate an optical-axis center point of an intermediate transfer belt. The first PD is arranged at a position at which specularly reflected light of light emitted from the first LED and diffused reflected light of light emitted from the second LED are received. The second PD is arranged at a position at which diffused reflected light of the light emitted from the first LED is received.

An image forming apparatus includes a first sensor configured to measure measurement images on a first photoreceptor, a second sensor configured to measure measurement images on an intermediate transfer member, and a controller. The controller controls a first image forming unit to form first measurement images, wherein the first measurement images are formed along a rotation direction of the first photoreceptor, and controls the first sensor to measure the first measurement images on the first photoreceptor. The controller further controls the first image forming unit and a second image forming unit to form a plurality of measurement images while a rotation speed of the first photoreceptor is being controlled based on a measurement result of the first sensor, wherein the plurality of measurement images are formed along the predetermined direction of the intermediate transfer member.

A printer includes a first printing unit responsible for one of preceding printing and subsequent printing that are to be performed on one sheet in overprinting, an other of the preceding printing and the subsequent printing being performed by a second printing unit; and a base-printing controller that causes the first printing unit to print a base for printing by the second printing unit in an operation of forming a test pattern for registration between the preceding printing and the subsequent printing on the sheet.

An image forming apparatus includes: a detecting unit configured to detect a test image formed on an image carrier; and an obtaining unit configured to obtain a color misregistration amount using a detection result of the test image by the detecting unit. The test image includes one or more basic patterns; each one of the one or more basic patterns includes a first pattern group and a second pattern group disposed at different positions in a conveyance direction of the image carrier; the first pattern group and the second pattern group each include a plurality of V-shaped patterns; and the V-shaped patterns of the first pattern group and the second pattern group have an axisymmetrical shape about an axis corresponding to a width direction orthogonal to the conveyance direction.

An image forming apparatus of an embodiment comprises a printer unit to print a sheet with a plurality of single colors and generate a correction sheet including a plurality of single color regions at different positions between a first reference region and a second reference region. The first and second reference regions are a reference color. An image reading unit is configured to read the correction sheet. A processor is configured to calculate a shift amount in a main scanning direction of the printer unit for each single color region based on RGB luminance values obtained from the correction sheet by the image reading unit and to correct a printer scan position along the main scanning direction for each single color in the plurality of single colors corresponding to the single color regions using calculated shift amounts.

A printing apparatus includes a printing device to print, on a sheet, a detection mark for acquiring an amount of deviation of an image, a detection device to read a position of the detection mark and acquire the amount of deviation of the position of the detection mark, and control circuitry to perform correction according to the amount of deviation. The circuitry prints the detection marks on both faces of the sheet in duplex printing, reads the detection marks on both faces with the detection device, calculates a first correction value from the position of the detection mark on a first face on which printing is performed first, calculates a second correction value from the position of the detection mark on a second face on which printing is performed later, and calculates a third correction value from the positions of the detection marks on the first and second faces.

An image forming apparatus is provided. The image forming apparatus includes a sensor to detect a toner concentration, and a processor to control a rendering of image-forming data to form an image on an image forming medium, according to a level of toner concentration saving that is adjusted based on the detected toner concentration.

An image forming apparatus is provided. The image forming apparatus includes an image forming part to form a pattern including at least one white dot line and at least one black dot line on an image forming medium using a photoconductive drum. A registration sensor is to sense an amount of light reflected from the image forming medium. A processor is to determine a state of the photoconductive drum based on the amount of sensed light in the pattern.

An image forming apparatus includes a plurality of photosensitive drums respectively corresponding to a plurality of colors to print, on a recording medium, color chart of a plurality of vertical lines in a sub-scanning direction to a main scanning direction of the recording medium and to be arranged at intervals along the main scanning direction. A vertical line of the plurality of vertical lines includes at least two colored sub-lines to be formed by corresponding at least two photosensitive drums. A processor is to perform a correction in non-linear color registrations in the main scanning direction using an image of the color chart.

A method for correcting cross-track position errors in a digital printing system having a linear printhead includes printing a test target including a plurality of alignment marks. A data processing system is used to automatically analyze a captured image of the printed test target to determine a measured position for each of the alignment marks. The measured positions for the alignment marks is compared to reference positions to determine measured cross-track position errors. A cross-track position correction function is determined responsive to the measured position errors, wherein the cross-track position correction function specifies cross-track position corrections to be applied as a function of cross-track position. A corrected digital image is determined by resampling the image lines of a digital image responsive to the cross-track position correction function.