In an image forming apparatus, an image forming unit configured to form a toner image on a transfer medium includes four sets of a photoconductor drum and a development roller, respectively, for forming toner images of first, second, third and fourth colors, arranged in this order, in a direction opposite to a direction of movement of the transfer medium moving toward a detector configured to detect a toner image formed on the transfer medium. A controller executes a bias-corrective test image forming process in which a first bias-corrective test image of the first color is arranged in a position downstream of other three first bias-corrective test images, and a second bias-corrective test image of the first color is arranged in a position between two first bias-corrective test images selected among other three first bias-corrective test images, in the direction of movement of the transfer medium.

An image forming apparatus includes: an image processor configured to perform image processing to image data based on a conversion condition to output converted image data; an image forming unit configured to form an image based on the converted image data output from the image processor, the image forming unit being controlled based on an image forming condition; a controller configured to perform tone correction control, density evenness control, and total density control that is combined the tone correction control and the density evenness control, wherein, in the tone correction control, the controller operates as follows: control the image forming unit to form a first test image on a sheet; obtain first reading data related to the first test image on the sheet.

An information processing apparatus includes: a setting unit configured to set one or more colorimetric regions in an image to be formed based on image data; and a transmission unit configured to transmit a print job to an image forming apparatus, the print job including the image data and colorimetric region information indicating the one or more colorimetric regions. The setting unit has a first mode under which the setting unit selects, based on a selection criterion, a colorimetric region in the image to be formed based on the image data, and a second mode under which a user designates the colorimetric region.

An image forming apparatus includes an image forming unit configured to form an image on a sheet, a discharge conveyance path configured to discharge the sheet on which the image is formed by the image forming unit to outside, a reverse conveyance path configured to reverse a conveyance direction of the conveyed sheet and convey the sheet, a first conveyance path configured to guide the sheet conveyed from the image forming unit to the reverse conveyance path, a second conveyance path configured to guide the sheet reversed in the reverse conveyance path from the reverse conveyance path to the discharge conveyance path, and a reading unit configured to read the image of the sheet in the second conveyance path.

An image forming apparatus includes an image processor configured to perform image processing on image data based on a conversion condition to output converted image data; an image forming unit configured to form an image based on the converted image data output from the image processor, the image forming unit being controlled based on an image forming condition; and a controller configured to perform tone correction control, density evenness control, and total density control, which is a combination of the tone correction control and the density evenness control. In the tone correction control, the controller controls the image forming unit to form a test image on a sheet and obtains reading data related to the test image on the sheet.

A color image processing apparatus includes an image forming unit configured to form a color image using recording materials of plural colors, an image processing unit configured to implement plural image processing methods that achieve plural types of pseudo-halftone representations, a color measurement unit configured to perform color measurement of the color image formed by the image forming unit, and a control unit configured to control execution of multi-color calibration in which the color measurement unit performs color measurement of a pattern image including plural multi-color patch images formed using recording materials of plural colors by using a smaller number of image processing methods than plural image processing methods used in single-color calibration for correcting reproduction characteristics of single-color images formed by the image forming unit and in which reproduction characteristics of a multi-color image formed by the image forming unit are corrected using a result of the color measurement.

An image forming apparatus includes an image forming unit configured to form an image on a sheet; a fixing unit configured to fix the image on the sheet; a reader configured to read a pattern image on the sheet downstream of the fixing unit in a conveying direction in which the sheet is conveyed; and a controller configured to control the image forming unit to form the image and the pattern image on a same sheet, control the fixing unit to fix the image and the pattern image on the same sheet, control the reader to read the pattern image on the same sheet, and control a density of an image to be formed on a sheet subsequent to the same sheet based on a result of reading the pattern image by the reader and reference data.

An image forming apparatus includes an image forming unit configured to form an image on a sheet; a fixing unit configured to fix the image on the sheet; a reader configured to read a pattern image on the sheet downstream of the fixing unit in a conveying direction in which the sheet is conveyed; and a controller configured to control the image forming unit to form the image and the pattern image on a same sheet, control the fixing unit to fix the image and the pattern image on the same sheet, control the reader to read the pattern image on the same sheet, and control a density of an image to be formed on a sheet subsequent to the same sheet based on a result of reading the pattern image by the reader and reference data.

An image forming apparatus includes a conveyance guide, a measurement unit, an opposing member, and a holding member. The conveyance guide has an opening and forms a conveyance path through which a sheet with an image formed on the sheet is conveyed. The measurement unit measures, through the opening, a color of the image on the sheet being conveyed through the conveyance path. The opposing member opposes the measurement unit at a measurement position of the measurement unit. The holding member holds the opposing member so that the opposing member is movable between a first position where the opposing member presses the sheet against the opening and a second position where the opposing member is separated from the opening as compared with the first position. The holding member includes an abutment portion that abuts against the conveyance guide in a state where the opposing member is at the first position.

An image density detector for detecting image density of an image borne by an image bearer includes a reference board, a light emitter, a light receiver, an image density calculator, and an image density detecting condition corrector. The reference board has a spectral reflectance distribution closer to a spectral reflectance distribution of the image forming material than a spectral reflectance distribution of white. The light emitter emits light to the reference board and the image borne by the image bearer. The light receiver receives the light reflected from the image and the reference board. The image density calculator calculates the image density of the image based on an output of the light receiver receiving the light reflected from the image. The image density detecting condition corrector corrects an image density detecting condition based on an output of the light receiver receiving the light reflected from the reference board.