An image forming apparatus comprises: an image forming unit for forming an image; a transfer member onto which the image is to be transferred; a transfer unit for transferring the image formed on the transfer member onto a sheet; a sensor for detecting reflected light from a detection image on the transfer member based on a detection condition; and a controller that controls the sensor to detect an area of the transfer member in which the image is not formed, generates the detection condition based on the result of detection of the area, controls the sensor to detect the detection image based on the detection condition, and controls a density of an image to be formed by the image forming unit, based on the result of detection of the detection image.

In the first charge amount acquisition operation, based on density of a plurality of toner images for measurement or based on a direct component of a developing current at the time of forming the plurality of toner images in addition to the density of the plurality of toner images for measurement, the charge amount acquisition section acquires a first toner charge amount that is a charge amount of toner included in the toner image for measurement. In the second charge amount acquisition operation, based on the toner density detected at the time of image formation and a relationship between the first toner charge amount and the toner density detected in the first charge amount acquisition operation, the charge amount acquisition section acquires a second toner charge amount that is a charge amount of the toner in the development device.

An image forming apparatus is provided. The image forming apparatus includes an image former to change a transfer condition while printing a calibration chart in which patches of different colors are repeatedly arranged in a sub-scanning direction, a scanner to scan the printed calibration chart, and a processor to determine an image defect under each transfer condition using the scanned calibration chart, and to set a transfer condition of the image former based on the determined image defect.

An image forming apparatus includes: a plurality of image forming parts each of which transfers a toner image to the transfer medium, the plurality of image forming parts being arranged from an upstream side to a downstream side along a moving direction of the transfer medium; a density detector that detects a density of the toner image; and a hardware processor that performs image stabilization control in which a plurality of patch images is formed while levels of parameters of image formation are changed for each of the image forming parts and the parameters are corrected based on respective densities of the patch images detected by the density detector.

An image forming apparatus controls a first image forming unit and a second image forming unit to form a plurality of pattern images. The plurality of pattern images includes a first pattern image formed by the first image forming unit, a second pattern image formed by the second image forming unit, a plurality of third pattern images that are formed by the first image forming unit and have different tones from one another, and a plurality of fourth pattern images that are formed by the second image forming unit and have different tones from one another. The image forming apparatus obtains data that has been output from a sensor and is related to the plurality of pattern images, and generates the conversion condition based on the data.

A controller controls a first image forming unit and a second image forming unit to form a test image having a pattern. The test image is formed by the first image forming unit based on a first image forming condition in which an absolute value of a developing potential of a first developing sleeve is greater than an absolute value of a charging potential of a first photosensitive member. The pattern is formed by a second image forming unit based on a second image forming condition in which an absolute value of a developing potential of a second developing sleeve is smaller than an absolute value of a charging potential of a second photosensitive member. A controller controls a sensor to read the test image having the pattern.

The image processing apparatus of the present invention includes: an edge determination unit configured to detect an edge pixel to which a white pixel and a black pixel are adjacent in a first direction in an image in which each pixel is represented as a white pixel or a black pixel; a first detection unit configured to detect a number of consecutive pixels up to the edge pixel in the first direction in the image; a second detection unit configured to detect a number of consecutive pixels whose number of consecutive pixels in the first direction is larger than a first threshold in a second direction perpendicular to the first direction in the image; and a type determination unit configured to determine a type of the edge pixel based on detection results by the first detection unit and detection results by the second detection unit.

An image forming apparatus includes an image bearing member; an image transfer device for transferring a toner image from aid image bearing member to a sheet; an application device for applying a transfer voltage to the image transfer device; and a controller for controlling an output mode operation for outputting a predetermined chart in which test halftone toner images transferred with different transfer voltages are formed to adjust the transfer voltage. When outputting a maximum size of the chart, the controller forms the test toner images in a region within 50 mm from an edge in a width direction perpendicular to a feeding direction of the sheet.

An image forming apparatus includes an image former that forms and fixes an image of the adjustment chart on the sheet, an image reader that reads the adjustment chart formed on the sheet, a front and back adjuster that performs the front and back adjustment on a basis of the adjustment chart that is formed and fixed by the image former and read by the image reader, an image coverage rate calculator that calculates in advance an image coverage rate of the sheet included in one job to be executed by the image former, and a chart coverage rate determiner that determines a coverage rate of the adjustment chart to be formed on a front side of the sheet on a basis of the image coverage rate calculated by the image coverage rate calculator.

A color imaging device includes a plurality of developer rolls with a common operating point, such as a common operating voltage. To determine the operating point, an acceptable range of color density is determined for each toner, the range being lighter and darker than an optimum color density for that toner. A search range is devised such that values within the range are examined relative to deviations from the optimum color density per each toner. The common operating point is selected as that having the lowest deviation per all toners. Also, if the common operating point corresponds to a color density darker than the acceptable range of color density for any toner, additional halftoning occurs compared to traditional halftoning, such as for continuous tones or solids. In this way, four color developer rolls can be operated from a single power supply, yet still provide acceptable color images.