An image reading apparatus acquires first image data of a background portion stored in advance and read by a reading unit, acquires second image data by reading the background portion, generates third image data by increasing resolution of the first image data and fourth image data by increasing resolution of the second image data, detects an amount of shift of an image sensor relative to a lens array in a predetermined direction by shifting a specific pixel range of the fourth image data relative to the third image data and comparing the specific pixel range with the third image data, and compares fifth image data obtained by shifting the fourth image data in accordance with the shift amount with the third image data, so as to determine whether each of pixels included in the fifth image data is a defective pixel having an abnormal value.

An image processing apparatus includes a reading unit and a controller. The reading unit radiates light to a target from two directions with different angles and reads images of the target. The controller performs, when controlling the reading unit to acquire the two images of the target, control such that a resolution of the image read by radiating the light to the target from one of the two directions is lower than a resolution of the image read by radiating the light to the target from the other one of the two directions.

An image forming apparatus performs the following. An imaging range imaged by each of the plurality of imaging sensors includes an overlapping portion between the imaging sensors adjacent in a width direction orthogonal to a conveying direction along the conveying path. A hardware processor performs a calibration operation of a first sensor based on a color measuring result of a predetermined inspection image measured within a standard imaging range of the first sensor among the plurality of imaging sensors, and a standard imaging result within the standard imaging range imaging an inspection image with a same pattern as the inspection image. The hardware processor compares imaging results by the plurality of imaging sensors in the overlapping portions and performs the calibration operation of another sensor different from the first sensor using the standard imaging result as a standard.

An image forming apparatus performs the following. An imaging range imaged by each of the plurality of imaging sensors includes an overlapping portion between the imaging sensors adjacent in a width direction orthogonal to a conveying direction along the conveying path. A hardware processor performs a calibration operation of a first sensor based on a color measuring result of a predetermined inspection image measured within a standard imaging range of the first sensor among the plurality of imaging sensors, and a standard imaging result within the standard imaging range imaging an inspection image with a same pattern as the inspection image. The hardware processor compares imaging results by the plurality of imaging sensors in the overlapping portions and performs the calibration operation of another sensor different from the first sensor using the standard imaging result as a standard.

According to examples, an apparatus may include a processor and a memory on which is stored machine readable instructions that are to cause the processor to determine a size of a chip gap between a first sensor chip and a second sensor chip, access a model that estimates an amount of positional shift of a target centroid, and apply the determined chip gap size and the accessed model on an image captured using the first sensor chip and the second sensor chip to compensate for an estimated positional shift in a centroid of a calibration target in the captured image by causing a location of the calibration target centroid in the captured image to more accurately correspond to an actual location of the calibration target centroid on an object from which the captured image was captured.

According to examples, an apparatus may include a processor and a memory on which is stored machine readable instructions that are to cause the processor to determine a size of a chip gap between a first sensor chip and a second sensor chip, access a model that estimates an amount of positional shift of a target centroid, and apply the determined chip gap size and the accessed model on an image captured using the first sensor chip and the second sensor chip to compensate for an estimated positional shift in a centroid of a calibration target in the captured image by causing a location of the calibration target centroid in the captured image to more accurately correspond to an actual location of the calibration target centroid on an object from which the captured image was captured.

An optical device includes a lens body including plural lenses of which optical axes are arranged alongside each other, and having an intermediate image forming surface for forming an erect real image of equal magnification formed in an optical path, a light shielding body that is provided to face a light incident surface of the lens body, and includes a transmitting portion that is positioned on the optical axes of the plural lenses and transmits light and a light shielding unit that is positioned on a portion other than the optical axes of the plural lenses and shields the passage of light, and a regulating body that is provided to face a light incident surface of the light shielding body, includes an opening narrower than the transmitting portion, and regulates a part of light toward the transmitting portion.

An image reading apparatus acquires first image data of a background portion stored in advance and read by a reading unit, acquires second image data by reading the background portion, generates third image data by increasing resolution of the first image data and fourth image data by increasing resolution of the second image data, detects an amount of shift of an image sensor relative to a lens array in a predetermined direction by shifting a specific pixel range of the fourth image data relative to the third image data and comparing the specific pixel range with the third image data, and compares fifth image data obtained by shifting the fourth image data in accordance with the shift amount with the third image data, so as to determine whether each of pixels included in the fifth image data is a defective pixel having an abnormal value.

An image processing apparatus that performs processes of reducing read data in a main-scanning direction and a sub-scanning direction, wherein the image reading apparatus includes a plurality of line image sensors having a longitudinal direction as the main-scanning direction, the plurality of line image sensors are displaced in the sub-scanning direction, and the image reading apparatus relatively moves the plurality of line image sensors and an original in the sub-scanning direction, wherein the image processing apparatus comprises: a sub-scanning direction processing unit configured to perform reduction processing in the sub-scanning direction; and a main-scanning direction processing unit configured to connect data after the reduction processing is performed by the sub-scanning direction processing unit in the main-scanning direction and reduces the connected data in the main-scanning direction.

An image processing apparatus that performs processes of reducing read data in a main-scanning direction and a sub-scanning direction, wherein the image reading apparatus includes a plurality of line image sensors having a longitudinal direction as the main-scanning direction, the plurality of line image sensors are displaced in the sub-scanning direction, and the image reading apparatus relatively moves the plurality of line image sensors and an original in the sub-scanning direction, wherein the image processing apparatus comprises: a sub-scanning direction processing unit configured to perform reduction processing in the sub-scanning direction; and a main-scanning direction processing unit configured to connect data after the reduction processing is performed by the sub-scanning direction processing unit in the main-scanning direction and reduces the connected data in the main-scanning direction.