An information processing apparatus includes a memory storing instructions and a processor to execute the instructions to perform operations. Four sides of a document included in captured image data are detected. Lengths of the detected four sides of the document are calculated. The operations further include determining which of a plurality of predefined paper sizes corresponds to the document based on the calculated lengths of the four sides. The determined corresponding paper size is set as a document size of the document.

A printer includes: a motor driving a transport member according to an operational parameter, to transport media along a media path from a media supply to a printhead; a first distance sensor disposed on a first side of the media path to measure a first distance between the media and the first distance sensor; and a controller configured to: receive the measured distance; detect curling of the media based on the first measured distance; and responsive to detecting curling of the media, update the operational parameter at the motor.

An image reader wherein a controller executes: a start process of starting a reading operation; a head edge detection process of detecting a document width; a first side edge detection process of detecting a side edge until an occurrence of a first change from a side edge detecting state to a side edge non-detecting state; a calculation process of calculating a continuation distance based on the document width; a second side edge detection process of detecting the side edge until an occurrence of a second change from the non-detecting state to the detecting state; a third side edge detection process of detecting the side edge until an occurrence of the first change; and an end process of ending the reading operation when the second change does not occur in a continuation range in the second detection process or when the first change occurs in the third detection process.

The image processing apparatus adds a first image that includes a predetermined image feature, to a read image of the document based on a detection result in the detecting, and transmits a second image of the predetermined image size specified in the read instruction, to the information processing apparatus. The information processing apparatus obtains the read image of the document included in the second image transmitted in the transmitting. The image processing apparatus adds the first image such that in the second image the first image is provided on the outside of the read image of the document, based on at least one of a width and a height of the document detected in the detection. The information processing apparatus obtains the read image of the document based on the predetermined image feature.

A detection device including a first belt stretched over a first pulley and a second pulley, a first sensor being fixed to the first belt, a second belt stretched over a third pulley and a fourth pulley to be arranged in parallel to the first belt, a second sensor being fixed to the second belt, a drive unit configured to generate a driving force for moving the first belt and the second belt, a first rotation shaft, the first pulley being fixed to the first rotation shaft, a second rotation shaft, the third pulley being fixed to the second rotation shaft, and a coupling unit configured to couple the first rotation shaft with the second rotation shaft, in which the coupling unit is configured to adjust an angle as viewed from an axial direction of one of the first rotation shaft and the second rotation shaft.

An image forming apparatus includes a conveyance part, an image forming part, a sheet detection sensor, a sensor unit, and a controller. The sheet detection sensor, in which a plurality of sensor blocks each with a plurality of sensor elements mounted thereon at specified intervals are arrayed in a sheet width direction, detects an edge position in the sheet width direction on a basis of scanning image data formed by reading of the sheet. The controller is enabled to execute a calibration of inserting, into the scanning image data, interpolation pixels for compensating an error between an edge position detected by the scanning image data and an actual edge position.

A multi-feed detection apparatus includes a conveyance roller, an ultrasonic sensor for generating an ultrasonic signal, an imaging device to image the medium being conveyed by the conveyance roller and sequentially generate a line image, and a processor to detect a width of the medium in each line image for each line image, detect a vertex count of a medium included in the sequentially generated line image based on the width of the media in the each line image, detect a length of the medium in a direction perpendicular to the medium width, estimate a shape of a medium based on the vertex count and the length of the medium, and detecting media multi-feed by comparing the ultrasonic signal with a predetermined threshold value, and change the predetermined threshold value or stop detection of the medium multi-feed, based on the estimated shape of the medium.

An image reading device includes: an image reading part that is disposed opposite paper conveyed along a conveyance path, and reads an image formed on the paper; and a hardware processor that performs an abnormality detection operation of detecting an abnormality in the image reading part, based on a first read image and a second read image that is different from the first read image in paper position at image reading time in a paper width direction orthogonal to a paper conveyance direction.

An image reading apparatus comprises a platen, a support, a reader, an open/close unit, a first obtainer, a mark, a positioning member, and a determiner. A position of the mark on a pressing surface of the cover, is provided at a position at which, in a case where a sheet of a maximum size among standard sizes that can entirely fit in a readable range of the reader is positioned with respect to the positioning member, at least a portion of the mark is not hidden by the sheet as viewed from the reader.

A document size detection device includes: a light source that irradiates a document placed on placing means with scanning light via the placing means; a reading unit that receives reflection light from the document via the placing means to acquire image data of the document; and circuitry to set an illumination depth of the scanning light at a size detection time when the size is detected, shallower than an illumination depth of the scanning light at an image reading time when an image of the document is read, and detects, at the size detection time, the size based on a difference between first image data acquired in a state in which the scanning light is switched off and second image data acquired in a state in which the scanning light is switched on.