An image reading device includes a reading unit, a background member, and processing circuitry. The reading unit includes alight source to emit light to a passage area through which an object passes and an imaging device to capture reflected light of the light emitted to generate a visible image and an invisible image. The background member is disposed opposite the light source across the passage area. The processing circuitry is configured to: detect a change in an image characteristic due to a change in an optical characteristic of the reading unit, in invisible images obtained by capturing of invisible marks on the background member; determine a correction amount of an image characteristic to be used for correcting an image of the object generated by the imaging device, based on the change in the image characteristic detected; and correct the image characteristic based on the correction amount determined.

Techniques are described for dynamically correcting image distortion during imaging of a patterned sample having repeating spots. Different sets of image distortion correction coefficients may be calculated for different regions of a sample during a first imaging cycle of a multicycle imaging run and subsequently applied in real time to image data generated during subsequent cycles. In one implementation, image distortion correction coefficients may be calculated for an image of a patterned sample having repeated spots by: estimating an affine transform of the image; sharpening the image; and iteratively searching for an optimal set of distortion correction coefficients for the sharpened image, where iteratively searching for the optimal set of distortion correction coefficients for the sharpened image includes calculating a mean chastity for spot locations in the image, and where the estimated affine transform is applied during each iteration of the search.

Techniques are described for dynamically correcting image distortion during imaging of a patterned sample having repeating spots. Different sets of image distortion correction coefficients may be calculated for different regions of a sample during a first imaging cycle of a multicycle imaging run and subsequently applied in real time to image data generated during subsequent cycles. In one implementation, image distortion correction coefficients may be calculated for an image of a patterned sample having repeated spots by: estimating an affine transform of the image; sharpening the image; and iteratively searching for an optimal set of distortion correction coefficients for the sharpened image, where iteratively searching for the optimal set of distortion correction coefficients for the sharpened image includes calculating a mean chastity for spot locations in the image, and where the estimated affine transform is applied during each iteration of the search.

A system is disclosed. The system includes at least one physical memory device to store compensation logic and one or more processors coupled with the at least one physical memory device to execute the compensation logic to generate transfer functions for each of a plurality of color planes to compensate for overlapping pel forming elements of adjacent printheads, wherein the transfer functions are generated based on ink deposition functions for groups of pel forming elements including non-overlapping pel forming elements and the overlapping pel forming elements, wherein the transfer functions transform input digital counts, and wherein the ink deposition functions represent output ink amount versus input digital count.

A printing system is disclosed. The printing system includes at least one physical memory device to store nozzle correction logic and one or more processors coupled with at least one physical memory device to execute the nozzle correction logic to receive a uniformity compensated halftone design for each of a plurality of pel forming elements, receive an average missing neighbor threshold lowering function, receive a defective nozzles list including one or more of the plurality of pel forming elements indicated as defective during print production and perform missing neighbor processing by applying the average missing neighbor threshold lowering function associated with a pel forming element determined to be a neighbor of a defective pel forming element.

A printing system is disclosed. The printing system includes at least one physical memory device to store calibration logic and one or more processors coupled with the at least one physical memory device to execute the calibration logic to generate a uniformity compensated halftone design for each of a plurality of pel forming elements, generate a missing neighbor corrected halftone design for each of the pel forming elements, generate a missing neighbor threshold lowering function for each of the pel forming elements based on the uniformity compensated halftone designs and the missing neighbor corrected halftone design and compute an average of the missing neighbor threshold lowering functions to generate an average missing neighbor threshold lowering function.

An image processing apparatus performs predetermined image processing for read data obtained by reading an image on a document by first and second reading sensors arranged so as to have an overlapping area. The predetermined image processing includes color correction processing of converting color signals detected by light receiving elements of the reading sensors into color signals with respect to each of pixels forming read data. Color correction processing for first read data obtained from light receiving elements of the first reading sensor not included in the overlapping area and color correction processing for second read data obtained from light receiving elements of the second reading sensor not included in the overlapping area are performed in accordance with different correction characteristics. By doing this, an image in which image unevenness caused by individual differences of the short reading sensors is reduced can be output.

A controller of an image reading device performs search for an edge candidate position inward from an edge portion in a main scanning direction of analysis image data in an extraction process of extracting a document region from read image data. When the retrieved edge candidate position corresponds to a dirt position, the search is continued whereas when the retrieved edge candidate position does not correspond to the dirt position, the document region is extracted from the read image data at the retrieved edge candidate position.

A printing system is disclosed. The printing system includes at least one physical memory device to store calibration logic and one or more processors coupled with the at least one physical memory device to execute the calibration logic to generate a uniformity compensated halftone design for each of a plurality of pel forming elements, generate a missing neighbor corrected halftone design for each of the pel forming elements, generate a missing neighbor threshold lowering function for each of the pel forming elements based on the uniformity compensated halftone designs and the missing neighbor corrected halftone design and compute an average of the missing neighbor threshold lowering functions to generate an average missing neighbor threshold lowering function.

An image reading device includes a reading unit, a background member, and processing circuitry. The reading unit includes alight source to emit light to a passage area through which an object passes and an imaging device to capture reflected light of the light emitted to generate a visible image and an invisible image. The background member is disposed opposite the light source across the passage area. The processing circuitry is configured to: detect a change in an image characteristic due to a change in an optical characteristic of the reading unit, in invisible images obtained by capturing of invisible marks on the background member; determine a correction amount of an image characteristic to be used for correcting an image of the object generated by the imaging device, based on the change in the image characteristic detected; and correct the image characteristic based on the correction amount determined.