A signal processing device includes a signal output circuit, a controller, and a corrector. The signal output circuit outputs a signal according to a physical quantity being input. The controller controls the signal output circuit. The corrector corrects a signal to be corrected. The signal to be corrected is output from the signal output circuit. The signal output circuit selectively performs one of first operation of outputting a characteristic signal that indicates characteristics of the signal output circuit and second operation of outputting a pseudo signal that is generated spuriously, according to control of the controller. The corrector corrects the signal to be corrected based on one of the characteristic signal and the pseudo signal output from the signal output circuit.

An image processing apparatus comprises: a first generation unit that generates approximate light pattern by adjusting spatial frequency of an input image, and generates a projection image data based on the approximate light pattern; and a second generation unit that generates a print image data based on the input image, wherein the second generation unit generates the print image data so that a difference between the input image and an image for observation obtained by superimposing projection light projected based on the projection image data onto a printed matter printed based on the print image data is reduced.

A document reading device includes: a conveying unit configured to convey a document; a background member having a mark for correcting an inclination of the document; a color reading unit configured to read an image of the document and to output color image data; a monochrome reading unit configured to read the image of the document and to output monochrome image data; a switching unit configured to switch between a first state and a second state; and a hardware processor configured to switch into the first state at the time of a color mode, and to switch into the second state at the time of the monochrome mode, configured to detect the inclination of the document, and configured to correct the inclination of the color image data, and to correct the inclination of the monochrome image data, in accordance with the detected inclination of the document.

An image reading apparatus according to an embodiment includes an image reading unit configured to generate reference data by reading a reference surface and to generate image data by reading a sheet. A reference unit has a reference surface. A shading correction unit determines whether a portion of the reference surface includes a contaminant based on image data generated by the image reading unit reading the portion of the reference unit. When the portion of the reference surface is determined to not include a contaminant, the shading correction unit generates reference data based on the image data generated by the image reading unit reading the portion of the reference surface determined to not include a contaminant.

An image reading apparatus including a controller configured to perform an update processing for updating shading correction data stored in a memory by a generation processing of generating shading correction data based on an image signal of a reference member and perform a size determination processing for determining a size of a document based on an image signal of the document, wherein, when the document on the document platen is read, the controller performs the generation processing before the document is read, and an image processing portion performs the shading correction using the shading correction data generated before the document is read, and wherein, when the size determination processing is performed, the image processing portion performs the shading correction using the shading correction data stored in the memory, and the update processing is not performed.

An image reading device includes: an FB glass; a sensor module having a light source and a plurality of sensors; and an image processor that generates correction data to be used for shading correction and performs the shading correction on image signals by using the correction data. The plurality of sensors is arranged in a main scanning direction and is configured to form an image signal on a single line. The image processor acquires second black data by causing the plurality of sensors to acquire an image signal of a reference sheet placed on the FB glass with the light source turned on, and generates black correction data based on the second black data. By performing the shading correction by using the black correction data, the image processor corrects density unevenness, in an image, caused by interference between image signals from the plurality of sensors.

An image reading apparatus according to an embodiment includes an image reading unit that generates reference data by reading a reference surface and generates image data by reading a sheet. A reference plate includes the reference surface for generating the reference data for shading correction of the image reading unit and a background surface for background of a sheet to be read to generate the image data. A control unit controls the positions of the image reading unit and the reference plate to be at a first position relative to each other when the reference data is to be generated and at a second position relative to each other when the image data is to be generated. The second position is different from the first position. A shading correction unit performs the shading correction in the image reading unit based on the generated reference data.

An image reading apparatus includes an image capturing module for capturing an image of a document, a light source, a movable light reflecting surface having a white color, a driving module for moving the light reflecting surface into a first position at which the light reflecting surface reflects light from the light source and a second position at which the light reflecting surface does not reflect light from the light source, and a control module for controlling the driving module to move the light reflecting surface. The control module determines the second position by moving the light reflecting surface by a predetermined quantity from the first position determined based on an image obtained by the image capturing module.

A document conveying and reading device includes a drive motor, a paper ejection roller driven by the drive motor, a first reading unit arranged along a document conveying path to face one surface of the document, and a shading roller arranged along the document conveying path to face the first reading unit. The shading roller includes a white reference member used for shading correction and a conveying guide for a document that is conveyed along the document conveying path, is driven by the drive motor together with the paper ejection roller when the drive motor drives the paper ejection roller to rotate in the second direction, and is not driven by the drive motor together with the paper ejection roller when the drive motor drives the paper ejection roller to rotate in the first direction.

An image reading apparatus according to an embodiment of the present invention includes: an image sensor to read a document; a movement unit configured to relatively move the document and the image sensor by using a motor as a drive source; an output unit configured to output data of a plurality of colors based on accumulated light-receiving signals by accumulating the light-receiving signals from the image sensor for each color in order for each line in a direction of the movement based on an encoder pulse output from an encoder in accordance with rotation of the motor; and a correction unit configured to perform shading correction for each piece of data of the plurality of colors output by the output unit by using a correction value to correct influence on data of the plurality of colors due to a dark current in the image sensor based on shading data.