Example implementations relate to a system comprising a memory resource to store instructions executable by a processing resource. In some examples, the processing resource can execute instructions to perform a calibration procedure for a printing device including a printing component. Responsive to the calibration procedure, the processing resource can execute instructions to deliver a print material arranged in a compound shape to a calibration image on the printing component included in the printing device. Responsive to performing the delivery, the processing resource can execute instructions to measure a print material density of the print material on the calibration image of the compound shape during the calibration procedure via a density sensor included in the printing device. Furthermore, the processing resource can execute instructions to detect an abnormality in the print material density via signal analysis instructions and provide a notification regarding the print material density abnormality.

An electrophotographic member comprises a base member and an elastic layer on the base member. The elastic layer contains a silicone rubber, an ionic electroconductive agent, and an inorganic particle, and the inorganic particle contains a hydroxide of at least one of magnesium or aluminum, and has a silicon atom on a surface thereof in an amount of 0.50 to 2.00 atomic %. An aqueous dispersion of which 5 mg of the inorganic particle is dispersed in 10 ml of water has a turbidity of 200 NTU or more and 1,240 NTU or less.

An image forming apparatus includes an image bearing member, an image forming unit, a detection unit, and a control portion. The detection unit includes a casing, an optical sensor, a shutter portion, a moving member, a groove portion, and a projection portion. The optical sensor is disposed within the casing facing the image bearing member to detect the toner image and comprises a light emitting portion emitting light to the image bearing member through the opening portion and a light receiving portion receiving the light reflected from the image bearing member. The shutter is configured to open/close the opening portion as the projection portion moves in a direction intersecting with the predetermined direction as the moving member moves in the predetermined direction. The groove portion is disposed perpendicularly above an extension line of an optical axis of the light irradiated from the light emitting portion to the image bearing member.

An image forming apparatus includes an image carrier, an image forming unit, a transfer unit, a detector, a controller, an edge detector, and an abnormality detector. The detector detects developer attached to an image carrying surface at a position between a position where an image is formed and a position where the image is transferred. The controller controls the image forming unit such that a check image including an edge that extends in a direction intersecting the moving direction of the image carrying surface is formed in a region of the image carrying surface that passes through the detection position. The edge detector determines a position of the edge based on a detection status of the developer. The abnormality detector determines whether or not the image former is abnormal based on the position of the edge.

An image forming apparatus includes a developing roller configured to develop an electrostatic latent image on a photosensitive drum to form a toner image; a belt onto which the toner image is transferred; a detection unit configured to detect a density of an image for detection formed on the belt; and a controller configured to perform hue adjustment based on a detection result of the detection unit. The image forming apparatus performs image formation in a second mode using a color gamut different from a color gamut in a first mode, and the controller obtains a lookup table, which indicates a correlation between image data to be used and input image data in the second mode, based on the detection result in the first mode and a correlation of density between the first mode and the second mode.

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 according to one embodiment includes an image carrier that moves in a first direction, a developing device, a detector, and a determination unit. The developing device uses a developer on the surface of the image carrier to forma strip-shaped image inclined with respect to the width direction perpendicular to the moving direction of the image carrier. The detector detects the density difference occurring in the strip-shaped image formed on the surface of the image carrier while moving in the width direction. The determination unit determines based on a detection result by the detector whether or not there is an abnormality.

An intermediate transfer belt that can bear a toner image includes a first layer and a second layer. The first layer includes a first surface located on an outer peripheral surface side of the first layer. The second layer is provided on a side of the first surface, transmits light, and includes a second surface. The first surface includes first grooves that (i) extend in a first direction in a circumferential direction of the intermediate transfer belt and (ii) are arranged in a width direction of the intermediate transfer belt that is orthogonal to the circumferential direction. The second surface is located on an outer peripheral surface side of the second layer, contacts a toner image, and includes second grooves that extend in a second direction in the circumferential direction. The first grooves includes 80 or more grooves per 1-mm length in the width direction in the first surface.

An image forming apparatus, configured to operate in first and second modes of which color gamut is different from each other, includes an exposure unit configured to expose a photosensitive drum; a developing roller configured to form a toner image; a detection unit configured to detect density of the toner image transferred to an intermediate transfer member; and a controller configured to adjust the density based on a value of input image data. A dithering process for the controller's controlling of the exposure unit is different depending on whether the operation is in the first mode or the second mode, and in at least a part of the input image data, the density of the toner image formed by the dithering process in the first mode is higher than the density of the toner image formed by the dithering process in the second mode.

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.