Abstract: A document placement detecting device includes a document table, a plate, a plurality of invisible light sources, an imaging device, and circuitry. The document table transmits light. The plate is openable and closable relative to the document table, and covers the document table in a closed state of the plate. The plurality of invisible light sources irradiate a placement area with invisible light via the document table. The placement area is an area of the document table on which a document is placed. The imaging device receives reflected light from the document, and outputs read data. The circuitry detects the placement of the document with a change in a read value of the read data output from the imaging device based on the irradiation with the invisible light.

Abstract: A document placement detecting device includes a document table, a plate, a plurality of invisible light sources, an imaging device, and circuitry. The document table transmits light. The plate is openable and closable relative to the document table, and covers the document table in a closed state of the plate. The plurality of invisible light sources irradiate a placement area with invisible light via the document table. The placement area is an area of the document table on which a document is placed. The imaging device receives reflected light from the document, and outputs read data. The circuitry detects the placement of the document with a change in a read value of the read data output from the imaging device based on the irradiation with the invisible light.

Abstract: A reading device includes a first light source, a second light source, a first reading unit, a second reading unit, a comparison unit, and a correction unit. The first source irradiates an object to be read, with first light having a first transmittance to the object. The second source irradiates the object with second light having a second transmittance to the object. The first reading unit reads the first light from the object to output first image data. The second reading unit reads the second light from the object to output second image data. The comparison unit compares a data difference between the first and second image data. In a case where the data difference is equal to or larger than a threshold, the correction unit corrects data of an image area having the data difference equal to or larger than the threshold in the first or second image data.

Abstract: A reading device includes a first light source, a second light source, a first reading unit, a second reading unit, a comparison unit, and a correction unit. The first source irradiates an object to be read, with first light having a first transmittance to the object. The second source irradiates the object with second light having a second transmittance to the object. The first reading unit reads the first light from the object to output first image data. The second reading unit reads the second light from the object to output second image data. The comparison unit compares a data difference between the first and second image data. In a case where the data difference is equal to or larger than a threshold, the correction unit corrects data of an image area having the data difference equal to or larger than the threshold in the first or second image data.

Abstract: 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.

Abstract: A reading device includes: a light source that irradiates a subject with scanning light; a light receiving section that receives reflection light from the subject; and circuitry to: control the light source to switch on and off of the scanning light; control the light receiver to receive the reflection light from the subject for a predetermined acquisition time at a predetermined acquisition interval so as to acquire data; and calculate a difference between the data acquired while the scanning light is switched on and the data acquired while the scanning light is switched off. The predetermined acquisition time and the predetermined acquisition interval are set such that the acquisition time or a total time of the acquisition time and the acquisition interval become an integer multiple of a fluctuation cycle of a fluctuation factor.

Abstract: A document size detection device includes: a light source to irradiate a document with light; an imaging device to receive light reflected at the document; and circuitry to control switch on and off of the light source and movement in a sub-scanning direction of the light source, and determine a size of the document based on image data acquired by the imaging device. The circuitry is to determine a size in a main-scanning direction of the document based on: first image data acquired when the light source is switched off while the light source is at a first reading position; second image data acquired when the light source is switched on while the light source is at the first reading position; and third image data acquired when the light source is switched on while the light source is being moved from the first reading position to a second reading position.

Abstract: 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.

Abstract: A reading device includes: a light source that irradiates a subject with scanning light; a light receiving section that receives reflection light from the subject; and circuitry to: control the light source to switch on and off of the scanning light; control the light receiver to receive the reflection light from the subject for a predetermined acquisition time at a predetermined acquisition interval so as to acquire data; and calculate a difference between the data acquired while the scanning light is switched on and the data acquired while the scanning light is switched off. The predetermined acquisition time and the predetermined acquisition interval are set such that the acquisition time or a total time of the acquisition time and the acquisition interval become an integer multiple of a fluctuation cycle of a fluctuation factor.

Abstract: A document size detection device includes: a light source to irradiate a document with light; an imaging device to receive light reflected at the document; and circuitry to control switch on and off of the light source and movement in a sub-scanning direction of the light source, and determine a size of the document based on image data acquired by the imaging device. The circuitry is to determine a size in a main-scanning direction of the document based on: first image data acquired when the light source is switched off while the light source is at a first reading position; second image data acquired when the light source is switched on while the light source is at the first reading position; and third image data acquired when the light source is switched on while the light source is being moved from the first reading position to a second reading position.