An image forming apparatus includes: a control unit configured to acquire base information by making a reading unit read a surface of the recording material with all image forming units set in a non-forming state, acquire first determination information by making the reading unit read a non-image region of the recording material with only a first image forming unit set in a forming state, and acquire second determination information by making the reading unit read the non-image region with all image forming units set in the forming state or with only all second image forming units set in the forming state. The control unit is further configured to determine a color of a toner adhered to the non-image region based on the base information, the first determination information, and the second determination information.

An image forming apparatus includes an image bearing member, an image transfer device for transferring a toner image from the 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.

In a case where an analysis result of image data of an (N+1)th page has not been acquired among image data, a fixing temperature for printing image data of an N-th page is determined at least based on a result of determination as to whether the image data of the N-th page and the image data of the (N+1)th page are similar and an analysis result of the image data of the N-th page.

An image forming apparatus includes: a control unit configured to acquire base information by making a reading unit read a surface of the recording material with all image forming units set in a non-forming state, acquire first determination information by making the reading unit read a non-image region of the recording material with only a first image forming unit set in a forming state, and acquire second determination information by making the reading unit read the non-image region with all image forming units set in the forming state or with only all second image forming units set in the forming state. The control unit is further configured to determine a color of a toner adhered to the non-image region based on the base information, the first determination information, and the second determination information.

Downtime relating to formation and detection of a detection image is reduced. An image forming apparatus includes a controller configured to calculate a first conversion unit to convert a gradation of input image data so that density output for the input image data becomes a first density output characteristic based on a first detection result of the detection image detected by a density sensor in a first mode. The controller generates a second conversion unit to convert the gradation of the input image data so that the density output for the input image data becomes a second density output characteristic in a second mode based on the detection result in the first mode and correction information, and further updates the correction information based on a second detection result of the detection image detected by the density sensor in the second mode and the first detection result.

An image forming apparatus includes an image bearer, an image forming section, an image density difference detector, and control circuitry. The image forming section is configured to form a gradation image pattern on a surface of the image bearer. The gradation image pattern includes gradation images having different image densities stepwise in a sub-scanning direction. The image density difference detector is configured to detect image density differences in a main scanning direction of the gradation images. The control circuitry is configured to execute an image density difference correction mode that corrects the image density differences in the main scanning direction based on detection results detected by the image density difference detector.

An image forming apparatus includes a converter configured to convert image data with use of a tone correction condition corresponding to a position in a main scanning direction of the image data, an image forming unit, which includes a photosensitive member and an exposure portion configured to expose the photosensitive member to light based on the converted image data, and is configured to form an image on a recording medium. The image forming apparatus further includes a holding portion configured to hold a plurality of feedback conditions corresponding to a plurality of tones and a controller configured to control the image forming unit to form a plurality of test images, acquire measurement results for the plurality of test images, and generate the tone correction condition based on the measurement results and the plurality of feedback conditions.

An image forming apparatus includes an image bearing member, an image forming portion, a transfer member, an applying portion, and an executing portion configured to execute an output operation for forming and outputting a chart formed on a recording material on which a plurality of test images are transferred by applying a plurality of voltages to the transfer member by the applying portion. The executing portion changes a change width per level of the test voltage so that the change width is a first change width in a case that a material of the recording material on which the chart is formed is a first material and so that the change width is a second change width different from the first change width in a case that the material of the recording material is a second material different from the first material.

An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference intensity information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

An image forming apparatus includes an image forming section, a measuring section, a generating section, and a predicting section. The image forming section forms an image on a sheet. The measuring section measures sound or vibration in the image forming section to obtain a measured result. The generating section generates frequency data through a frequency analysis of the measured result. The predicting section predicts a malfunction to occur of the image forming section based on the frequency data.