A measurement apparatus includes a first conveyance path, a second conveyance path, a measuring portion, a third conveyance path and a sheet stacking portion. A sheet discharged out of an image forming apparatus is conveyed toward a downstream apparatus through the first conveyance path. The second conveyance path is branched from the first conveyance path, extended below the first conveyance path, and merged with the first conveyance path. The measuring portion is disposed on the second conveyance path. The third conveyance path is provided above the first conveyance path and is configured to convey the sheet from which a test image has been measured by the measuring portion in the second conveyance path. The sheet stacking portion is provided above the first conveyance path, and the sheet discharged out of the third conveyance path is stacked on the sheet stacking portion.

An image forming unit forms an image based on image data. A roller conveys the sheet from a tray. A reading unit reads the sheet. A controller controls the image forming unit to form a test image on one side of the sheet, controls the roller to convey the sheet on which the test image has been formed, obtains first read data relating to a read result of a first surface of the sheet on which the test image is formed, obtains second read data relating to a read result of a second surface from the first read data and the second read data, selects read data relating to a read result relating to the test image, controls, based on the selected read data, a density of an output image to be formed by the image forming unit.

A measurement apparatus includes a sheet stacking portion provided above a first conveyance path and on which a second sheet discharged out of a second conveyance path is stacked. The sheet stacking portion includes an extension tray configured to support the sheet discharged out of the second conveyance path and to be movable between a first position and a second position, the first position being a position where the extension tray is located inside a width of the measurement apparatus in the horizontal direction, and the second position being a position where the extension tray is located above an upstream apparatus and is overlapped with the upstream apparatus when viewed in a gravity direction.

An image forming apparatus includes an image forming device, an image position detector, and an image density detector. The image forming device forms an image on a surface of a recording medium. The image position detector detects a position of the image. The image density detector detects a density of the image. The image forming device forms a position detection image on a surface of a first recording medium. The image position detector detects a position of the position detection image on the surface of the first recording medium. The image forming device forms a density detection image on a second recording medium. The image density detector detects a density of the density detection image on the surface of the second recording medium.

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 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.

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.

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, including: an image former; and a hardware processor which detects a density of an image formed by the image former, controls the image former to continuously perform image formation on a predetermined number of sheets and thereafter form a plurality of types of halftone test images on a sheet, determines whether an image defect is generated and determines a factor causing the image defect by analyzing densities of the plurality of types of test images, executes a recovery mode which is set for each of the factor when the image defect is determined to be generated, and controls the image former to form a charged test image which is formed by the charger charging the surface of the image carrier and an uncharged test image which is formed without charging of the surface of the image carrier by the charger.

An apparatus converts image data based on a conversion condition, forms an image using a developer, measures the developer, and measures humidity. The apparatus determines a first density of an image when a mode of the apparatus changes from a power saving mode in which the apparatus cannot form an image to a normal mode in which the apparatus can form an image, from values measured, based on a first determination condition, determines a second density of an image when the apparatus has formed images on a predetermined number of sheets in the normal mode, from values measured, based on a second determination condition that is different from the first determination condition, and generates the conversion condition based on the first density and the second density.