A color accuracy verification device includes: a hardware processor that: acquires a colorimetric value for each color patch of color accuracy verification charts generated by a plurality of printers; stores the colorimetric value in time series; sets a target printer to carry out color accuracy verification; and verifies color accuracy based on: the colorimetric value of the target printer stored in the hardware processor; and a verification reference value set in advance; and a display that displays a verification result by the hardware processor for the target printer.

An image forming apparatus includes: an image. forming unit configured to form an image on an image bearing member based on an image forming condition, an optical sensor including: a light emitter configured to irradiate the image bearing member with light based on a supplied current; and a light receiver configured to receive reflected light of the light emitted from the light emitter; a temperature detector configured to detect a temperature of the optical sensor; and a controller configured to: control the image forming unit to form a detection image on the image bearing member; control the optical sensor to detect reflected light from the detection image; and adjust the image forming condition based on a result of detecting the detection image by the optical sensor. The controller is configured to control the light emitter to emit light; and generate a correction condition.

In an example, a method includes printing a set of images by transferring print agent between a roller of a print agent source and an electrophotographic surface in a plurality of transfer operations, wherein the roller is controlled to have a first voltage profile during each of the transfer operations. A variation in optical density which is consistent across the set of printed images may be detected, and a second voltage profile correction may be determined based on the variation in optical density. The method may further comprise printing a subsequent image by transferring print agent between the print agent source roller and the electrophotographic surface in a subsequent transfer operation, wherein the roller is controlled to have the second voltage profile during the subsequent transfer operation.

An image forming apparatus includes a detection unit that optically detects a density of a reference toner image for density measurement formed on an image carrier. Either a first detection method for detecting the density of the reference toner image by receiving specularly reflected light reflected by the image carrier and the reference toner image for density measurement formed on the image carrier or a second detection method for detecting the density of the reference toner image by receiving diffusely reflected light from the image carrier and the reference toner image, is selected in accordance with color information of a toner, the color information being stored beforehand in a storage unit, and the density of the reference toner image is optically detected.

An image forming apparatus includes a toner charge amount predictor, a toner developing resistance calculator, and a determiner. The toner developing resistance calculator calculates a toner developing resistance on the basis of a bias voltage applied to a developing device and a measured developing current by dividing a value of the bias voltage by a value of the developing current when a developing device develops an electrostatic latent image formed on the surface of an image carrier to form a toner image. The toner charge amount predictor predicts a toner charge amount of a toner which is supplied to the image carrier by the developing device on the basis of a density of the toner image and the developing current. The determiner determines a state of the developing device on the basis of the toner charge amount and the toner developing resistance.

An image forming apparatus includes: a photoconductor; a transfer portion; a photoconductor cleaner that removes residual toner from a surface of the photoconductor; and a first processor that forms a toner patch on the surface of the photoconductor. When the toner patch passes the transfer portion, the transfer portion makes the toner patch stay on the surface of the photoconductor such that toner of the toner patch is able to be supplied to the photoconductor cleaner. The first processor further determines an amount of toner for the toner patch with reference to a circumferential distance the photoconductor travels for a predetermined period of time.

An image processing apparatus includes a read image obtaining unit configured to obtain read image data indicative of an image having been read, a target generation unit configured to generate, based on the read image data, target data indicative of a target color of a print medium, and a gradation correction unit configured to correct, based on the target data, a gradation of print image data indicative of an image to be formed.

An image forming apparatus includes an image processor configured to convert image data based on a first conversion condition; an image forming unit configured to form an image on a sheet based on the image data converted by the image processor, the image forming unit having an image bearing member on which the image is to be formed, a transfer unit configured to transfer the image from the image bearing member onto the sheet, and a fixing unit configured to fix the image to the sheet; a conveyance roller configured to convey the sheet having the image fixed thereto; a reading unit configured to read a pattern image on the sheet conveyed by the conveyance roller; and a detector configured to detect a pattern image on the image bearing member.

A printing apparatus includes: plural image forming units accommodating colorants of the same color; and a controller that forms an image of one color using the plural image forming units.

An image forming apparatus includes a platen on which an original is to be placed, a feeder configured to feed an original placed on a tray, a sensor configured to detect a sheet on the tray, a lamp provided to the feeder, a reader configured to read the original placed on the platen and to read the original conveyed by the feeder, an image forming unit configured to form an image on a sheet, and a controller. The controller is configured to control the image forming unit to form a first test image on a sheet, control the reader to read the first test image formed on the sheet placed on the platen, control a density of the image to be formed by the image forming unit based on a reading result of the first test image.