An apparatus includes, a change unit configured to change a pixel value of an edge pixel indicating an edge portion of an image based on the image data having the quantized color, wherein, in a case where the pixel value of the edge pixel is a pixel value changed by color reduction processing to decrease a luminance, the change unit changes the pixel value of the edge pixel to a pixel value of a pixel having a highest luminance among pixels surrounding the edge pixel, and wherein, in a case where the pixel value of the edge pixel is a pixel value changed by the color reduction processing to increase a luminance, the change unit changes the pixel value of the edge pixel to a pixel value of a pixel having a lowest luminance among pixels surrounding the edge pixel.

An image processing device is provided that enables an operator to reduce time and effort, and that enables an image to be read stably without receiving the influence of a shadow generated after calibration. The image processing device includes: a tint component removing unit that removes a tint component from a captured image; a character information removing unit that removes character information from an image obtained by removing the tint component; a dividing unit that performs grouping on the captured image according to a combination of hue and saturation; a calculating unit that calculates, for each group, correction data for correcting the shadow in accordance with an image obtained by removing the character information and an image obtained by grouping; and a correcting unit that corrects the captured image in accordance with the calculated correction data.

An image processing device is provided that enables an operator to reduce time and effort, and that enables an image to be read stably without receiving the influence of a shadow generated after calibration. The image processing device includes: a tint component removing unit that removes a tint component from a captured image; a character information removing unit that removes character information from an image obtained by removing the tint component; a dividing unit that performs grouping on the captured image according to a combination of hue and saturation; a calculating unit that calculates, for each group, correction data for correcting the shadow in accordance with an image obtained by removing the character information and an image obtained by grouping; and a correcting unit that corrects the captured image in accordance with the calculated correction data.

A first conversion into pixels of an obtained object, for which the processing for widening the width of the object is performed, is performed, and a second conversion into pixels of the object, for which the processing for widening the width of the object is not performed, is performed. When the first conversion is performed, a pixel is filled or is not filled with color depending on a position of a boundary of the object in the pixel. When the second conversion is performed, a pixel is filled with color if the position of the boundary of the object exists in the pixel.

A color fringe is corrected by detecting a transition region that includes pixels adjacent in a linear direction. A color difference distribution in the transition region is modeled by a logistic function. Pixel color values in the transition region are corrected using the logistic function to maximize a correlation between a correction color and a reference color with respect to the transition region. Color distortion such as color fringes is corrected without corrupting the original colors of the image by modeling the color difference by the logistic function while maximizing the correlation using information of the undistorted region. A calculation cost is reduced by reducing the number of the parameters required to optimize the logistic function.

Embodiments of the present disclosure provide an image calibration method, an image forming apparatus, and a storage medium. The method includes outputting a calibration image in response to a calibration instruction, where the calibration image includes a calibration pattern and a calibration mark; according to the calibration mark of the calibration image, determining whether a calibration event corresponding to the calibration image matches a calibration event corresponding to a current calibration operation, or determining whether a calibration event type corresponding to the calibration image matches a calibration event type corresponding to a current calibration operation; and performing image calibration according to the calibration pattern in the calibration image if the calibration event corresponding to the calibration image matches the calibration event corresponding to the current calibration operation, or if the calibration event type corresponding to the calibration image matches the calibration event type corresponding to the current calibration operation.

An image inspection device detects an abnormality of a formed image by comparing imaged data obtained by imaging the formed image with original image data of the formed image. The image inspection device includes a hardware processor that: adjusts the original image data to reduce sharpness of the original image data; and detects the abnormality by comparing the adjusted original image data with the obtained imaged data. The hardware processor partly restricts the reduction of the sharpness.

An image inspection device detects an abnormality of a formed image by comparing imaged data obtained by imaging the formed image with original image data of the formed image. The image inspection device includes a hardware processor that: adjusts the original image data to reduce sharpness of the original image data; and detects the abnormality by comparing the adjusted original image data with the obtained imaged data. The hardware processor partly restricts the reduction of the sharpness.

A restoration filter generation device which generates a restoration filter for performing a restoration process on luminance system image data, the restoration process being based on a point-image distribution in an optical system, the luminance system image data being image data relevant to luminance and being generated based on image data for each color of multiple colors, the restoration filter generation device including an MTF acquisition device which acquires a modulation transfer function MTF for the optical system; and a restoration filter generation device which generates the restoration filter based on the modulation transfer function MTF, the restoration filter suppressing an MTF value of image data for each color of the multiple colors to 1.0 or less at least in a region of a particular spatial frequency or less, the image data for each color of the multiple colors corresponding to the luminance system image data after the restoration process.

A restoration filter generation device which generates a restoration filter for performing a restoration process on luminance system image data, the restoration process being based on a point-image distribution in an optical system, the luminance system image data being image data relevant to luminance and being generated based on image data for each color of multiple colors, the restoration filter generation device including an MTF acquisition device which acquires a modulation transfer function MTF for the optical system; and a restoration filter generation device which generates the restoration filter based on the modulation transfer function MTF, the restoration filter suppressing an MTF value of image data for each color of the multiple colors to 1.0 or less at least in a region of a particular spatial frequency or less, the image data for each color of the multiple colors corresponding to the luminance system image data after the restoration process.