An image reading apparatus includes an imaging device for generating a white reference image of a white reference member and a document image of a document and a periphery of the document, and a processor for performing first processing for detecting a dirt substance from the white reference image, generating data for shading correction based on the white reference image, correcting the document image using the data for shading correction to generate a correction image, and performing second processing for detecting a dirt substance from the correction image. One of the first processing or the second processing is performed using a dirt substance detection result of the other one of the first processing or the second processing.

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.

A printing apparatus includes a printer with printing elements that print dots and a controller that controls the printer on the basis of input image data. The controller acquires a pre-correction printing density that is based on test pattern data, which includes a uniform array of pixels, and printing characteristics of a dot size of the printing elements. The controller calculates a target density by averaging the pre-correction printing density and offsets the target density so that the target density is equal to or greater than the pre-correction printing density. The controller calculates a correction gain of the printing elements on the basis of the ratio of the target density to the pre-correction printing density and controls the printer on the basis of the correction gain and the input image data.

In an example, two images of a printed calibration image are acquired using two measurement devices. The measurement devices are offset along an axis so that the two images correspond to two portions of the printed calibration image overlapping along the axis. The printed calibration image comprises a pattern extending across the printed calibration image in the direction of the axis, the pattern defining a shape so that in each image, a portion of the pattern appears as different from a straight line parallel to the axis. The two images are aligned using the two portions of pattern.

An image scanner includes: a document table; a document cover; a light source; an image sensor; and a circuit configured to: acquire, as pre-reading black data, the line data that is generated by the image sensor in a state where the light source is turned off; after acquiring the pre-reading black data, acquire, as line image data, the line data that is generated by the image sensor in a state where light is emitted from the light source to an original document supported on the document table; after acquiring the line image data, acquire, as post-reading black data, the line data that is generated by the image sensor in a state where the light source is turned off; determine black reference data based on the post-reading black data and the pre-reading black data; and perform black correction on the line image data based on the black reference data.

An image processing device includes: a sensor that reads a print region and a non-print region of a print medium, an image being printed in the print region, the non-print region being a blank area; and a controller that makes shading correction for an output from the sensor, based on a read result from the sensor. The controller sets a patch image printed in the print region to a black reference, sets the non-print region to a white reference, and makes the shading correction, based on properties of the black reference and the white reference at individual locations.

A continuous reading mode is a mode in which reading of a document placed on a contact glass is continued and a job is started after completion of reading is accepted. In reading of the second and subsequent sheets of the document in a set reading range, a reading controller does not move the position of the reading line of an image sensor to outside the end position of the reading range in the sub-scanning direction as seen from a home position.

An information processing apparatus generates a second profile for reproducing, on a recording medium having a fluorescent characteristic, a color defined in a first profile. The information processing apparatus includes a processor configured to acquire, as a white color value of the recording medium, a colorimetric value obtained by colorimetric measurement of the recording medium under a colorimetric condition using a light source including ultraviolet rays; set a white reference value different from the white color value, based on the white color value; acquire, as a first target value, a color value in a Lab uniform color space defined by the first profile; acquire, as a second target value, a color value obtained by converting the acquired color value, based on the white reference value; and set the second target value with respect to a gamut having a chroma that is less than a first chroma.

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 method of balancing responses of a plurality of sensor chips arranged generally in a linear array comprising: exposing the plurality of sensor chips to an absence of illumination; measuring a dark response of each photosensor of a plurality of photosensors; positioning a calibration piece within a field of view of the plurality of sensor chips other than a calibration sensor chip; illuminating a calibration standard and the calibration piece with a light source; measuring a light response of each photosensor of the plurality of photosensors; applying an offset to the light response of each photosensor of the plurality of photosensors by subtracting the dark response of each photosensor of the plurality of photosensors to obtain an offset light response for each photosensor of the plurality of photosensors; calculating a mean offset light response for each sensor chip of the plurality of sensor chips by averaging the offset light response for each photosensor of the plurality of photosensors in each sensor chip of the plurality of sensor chips; calculating a modified light response for each photosensor of the plurality of photosensors by modifying the offset light response for each photosensor of the plurality of photosensors based on the mean offset light response of the sensor chip comprising the respective photosensor, the mean offset light response of the calibration sensor chip, an initial mean offset light response of the sensor chip comprising the respective photosensor, and an initial mean offset light response of the calibration sensor chip; and, applying a first gain to the offset light response of each photosensor of the plurality of photosensors based on the modified light response of each respective photosensor to obtain a corrected light response of each photosensor of the plurality of photosensors.