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 gain modification device (20) includes a plurality of gain modification units (31) whose number of units corresponds to a number of kinds of a plurality of signals input to the plurality of gain modification units, each one of the plurality of gain modification units (31) being configured to modify a gain value used to amplify the plurality of signals, and a plurality of gain reflection control units (44) configured to change a timing at which the gain value is to be switched by the plurality of gain modification units (31) such that the gain value of one of the plurality of signals affecting a signal level of another one of the plurality of signals is switched at a timing different from a timing at which the gain value of the another one of the plurality of signals is switched.

Abstract: A signal correction device includes a correction signal generator configured to generate a correction signal serving to remove noise superimposed on an input signal; a phase adjuster configured to shift a phase of the correction signal generated by the correction signal generator; a subtractor configured to generate an output signal for output by subtracting the correction signal from the input signal; a peak and bottom detector configured to detect a peak value and a bottom value of the output signal; and a determiner configured to determine a phase-shift amount of the phase adjuster from the peak value and the bottom value of the output signal detected by the peak and bottom detector. The determiner detects uncorrected noise from the peak value and the bottom value of the output signal from the subtractor, and sets the phase-shift amount such that the uncorrected noise is reduced to a minimum.

Abstract: An inclination detecting device includes processing circuitry. The processing circuitry is configured to detect, in image information that is an image of an object imaged by an imaging device at an imaging position where a background member forms a background, a first boundary between the background member and a shadow of the object; detect a second boundary between the object and the shadow of the object in the image information; and detect an inclination of the object in the image information from the first boundary and the second boundary detected by the processing circuitry.

Abstract: An edge detecting device includes processing circuitry. The processing circuitry is configured to acquire first color information and second color information in an image including a document region and a background region outside the document region. The first color information is color information of the background region and the second color information is color information of the document region. The processing circuitry is configured to detect a boundary between the background region and the document region from a change in color information between the first color information and the second color information.

Abstract: A sheet reading apparatus includes a sheet table on which a sheet is placed, a conveyor configured to convey the sheet, a reading guide configured to guide the sheet conveyed by the conveyor, and a reading device configured to read a shadow of the sheet conveyed by the conveyor, for detection of an inclination of the sheet. The sheet reading apparatus further includes a transparent member disposed at a position on a reading line of the reading device. The position on the reading line is withdrawn from the sheet and adjacent to the reading guide.

Abstract: An inclination detecting device includes processing circuitry. The processing circuitry is configured to detect, in image information that is an image of an object imaged by an imaging device at an imaging position where a background member forms a background, a first boundary between the background member and a shadow of the object at detection positions in at least one of main-scanning and sub-scanning directions on an outline of the object; detect a second boundary between the object and the shadow of the object at detection positions in at least one of the main-scanning and sub-scanning directions on the outline of the object in the image information; detect a boundary group including detection results of the second boundary at the detection positions; and detect an inclination of the object in the image information from detection results of the first boundary, the second boundary, and the boundary group.

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 signal correction device includes a correction signal generator configured to generate a correction signal serving to remove noise superimposed on an input signal; a phase adjuster configured to shift a phase of the correction signal generated by the correction signal generator; a subtractor configured to generate an output signal for output by subtracting the correction signal from the input signal; a peak and bottom detector configured to detect a peak value and a bottom value of the output signal; and a determiner configured to determine a phase-shift amount of the phase adjuster from the peak value and the bottom value of the output signal detected by the peak and bottom detector. The determiner detects uncorrected noise from the peak value and the bottom value of the output signal from the subtractor, and sets the phase-shift amount such that the uncorrected noise is reduced to a minimum.

Abstract: An image processing apparatus includes circuitry to: obtain a read image read from an image of a document output from an image reading device; detect an edge between a background area and a document area in the read image; sample a detection result of the edge at each first interval in a first direction to extract a first boundary point group including a plurality of boundary points; sample the detection result of the edge at each second interval in the first direction to extract a second boundary point group including a plurality of boundary points; determine a noise removal condition based on the first boundary point group; remove, from the second boundary point group, a boundary point satisfying the noise removal condition as noise; and calculate a linear equation approximating the second boundary point group from which the noise is removed.

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: An edge detecting device includes processing circuitry. The processing circuitry is configured to acquire first color information and second color information in an image including a document region and a background region outside the document region. The first color information is color information of the background region and the second color information is color information of the document region. The processing circuitry is configured to detect a boundary between the background region and the document region from a change in color information between the first color information and the second color information.

Abstract: An image processing apparatus includes circuitry to: obtain a read image read from an image of a document output from an image reading device; detect an edge between a background area and a document area in the read image; sample a detection result of the edge at each first interval in a first direction to extract a first boundary point group including a plurality of boundary points; sample the detection result of the edge at each second interval in the first direction to extract a second boundary point group including a plurality of boundary points; determine a noise removal condition based on the first boundary point group; remove, from the second boundary point group, a boundary point satisfying the noise removal condition as noise; and calculate a linear equation approximating the second boundary point group from which the noise is removed.

Abstract: An inclination detecting device includes processing circuitry. The processing circuitry is configured to detect, in image information that is an image of an object imaged by an imaging device at an imaging position where a background member forms a background, a first boundary between the background member and a shadow of the object at detection positions in at least one of main-scanning and sub-scanning directions on an outline of the object; detect a second boundary between the object and the shadow of the object at detection positions in at least one of the main-scanning and sub-scanning directions on the outline of the object in the image information; detect a boundary group including detection results of the second boundary at the detection positions; and detect an inclination of the object in the image information from detection results of the first boundary, the second boundary, and the boundary group.

Abstract: An inclination detecting device includes processing circuitry. The processing circuitry is configured to detect, in image information that is an image of an object imaged by an imaging device at an imaging position where a background member forms a background, a first boundary between the background member and a shadow of the object; detect a second boundary between the object and the shadow of the object in the image information; and detect an inclination of the object in the image information from the first boundary and the second boundary detected by the processing circuitry.

Abstract: A sheet reading apparatus includes a sheet table on which a sheet is placed, a conveyor configured to convey the sheet, a reading guide configured to guide the sheet conveyed by the conveyor, and a reading device configured to read a shadow of the sheet conveyed by the conveyor, for detection of an inclination of the sheet. The sheet reading apparatus further includes a transparent member disposed at a position on a reading line of the reading device. The position on the reading line is withdrawn from the sheet and adjacent to the reading guide.

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.