An original image is read as an aggregate of a plurality of pixels in which adjacent pixels have different colors (R, G, and B) in a main scanning direction and in a sub-scanning direction, and the read pixels of the respective colors are stored in a line memory in association with information on relative positions of the pixels with respect to another pixel. Then, the stored pixels are sorted so that pixels having the same color are adjacent to each other, and an abnormal pixel (dust) not present in the original image is detected based on the state of the sorted pixels. With this, the dust not present in the original image is detected without increasing the cost, and the dust is corrected without forming a conspicuous trace of correction.

Disclosed is a method of processing data from an image scanner for reducing image artefacts. The image scanner comprises a first image sensor arranged to: record a first set of lines, the first set of lines comprising a plurality of pixels representing recorded intensities of a first colour, record a second set of lines, the second set of lines comprising a plurality of pixels representing recorded intensities of a second colour; and record a third set of lines, the third set of lines comprising a plurality of pixels representing recorded intensities of a third colour. The method comprises the steps of: processing at least two of the first, the second or the third set of lines to create a first combined set of lines and filtering said first combined set of lines to filter out image artefacts creating a first filtered combined set of lines.

An image acquisition apparatus, an image forming apparatus, and a control method of the same are provided. An image acquisition apparatus includes an image sensor in which a red element outputting a signal corresponding to a red light, a green element outputting a signal corresponding to a green light, and a blue element outputting a signal corresponding to a blue light are arranged in a predetermined pattern, a driving unit configured to move the image sensor to a plurality of positions; and an image processor configured to receive a signal output from the red element, the green element and the blue element in the plurality of positions, respectively, and configured to acquire an image of an object by combining the received signal.

An image reading apparatus includes a front-side reader, which includes a white LED configured to irradiate an original with light and a CMOS sensor configured to receive light that is reflected by the original. The front-side reader is configured to generate read data that represents a luminance value of an image on the original from the result of receiving light with the CMOS sensor. The image reading apparatus stores, in a non-volatile memory, a condition for determining whether there is a sub-scanning color shift, and uses a sub-scanning color shift detector to determine whether there is a sub-scanning color shift based on the read data obtained from the front-side reader and the condition stored in the non-volatile memory. When there is a sub-scanning color shift, the image reading apparatus corrects the sub-scanning color shift by correcting the read data with a color shift corrector.

An original image is read as an aggregate of a plurality of pixels in which adjacent pixels have different colors (R, G, and B) in a main scanning direction and in a sub-scanning direction, and the read pixels of the respective colors are stored in a line memory in association with information on relative positions of the pixels with respect to another pixel. Then, the stored pixels are sorted so that pixels having the same color are adjacent to each other, and an abnormal pixel (dust) not present in the original image is detected based on the state of the sorted pixels. With this, the dust not present in the original image is detected without increasing the cost, and the dust is corrected without forming a conspicuous trace of correction.

An image scanner is configured to: while changing a reading position by a position changer and sequentially emitting light of each of three colors in a turn-on sequence from a light source to a document, control a line sensor to read reflection light of emitted light, thereby acquiring gradation image data including gradation values of three colors for each pixel in one line; determine whether a top color shift occurs in the gradation image data at a determination position; in response to determining that the top color shift occurs at the determination position, replace gradation image data at the determination position with black image data; determine whether a bottom color shift occurs in the gradation image data at the determination position; and in response to determining that the bottom color shift occurs at the determination position, replace gradation image data at the determination position with white image data.

An image reading apparatus comprises a light source for repeatedly emitting first light having a first color, second light having a second color and third light having a third color toward a read target while moving the light source in a sub-scanning direction, first, second, and third sensors, each configured to sense a strength of first, second, and third reflected light, respectively, in a light reflected from the read target, and to output first, second, and third signal waveforms corresponding to the strength of the first, second, and third reflected light, respectively, and a controller. The controller is configured to execute a line-to-line correction for correcting a phase shift between the first, second, and third signal waveforms, and to correct a shift in a signal level caused by the line-to-line correction.

An image processing method includes: extracting a red, green and blue channel image and a white channel image from a target image; determining a first gray-scale component image of the red, green and blue channel image, and determining a second gray-scale component image of the white channel image; determining first decomposed sub-band information of the first gray-scale component image, and determining second decomposed sub-band information of the second gray-scale component image; determining third decomposed sub-band information according to the first decomposed sub-band information and the second decomposed sub-band information; performing image reconstruction according to the third decomposed sub-band information to obtain a third gray-scale component image, and constructing a color image corresponding to the target image according to the third gray-scale component image. An apparatus and storage medium incorporate the image processing method.

An image correction method includes: acquiring band images obtained by imaging a subject, and a high-resolution image having a resolution higher than that of the band images; acquiring a position difference between the object band image and the reference band image among the band images; by using a pixel of the object band image as an object pixel, for each object pixel, determining a pixel value of each sub-region obtained by dividing the imaging region of the object pixel into a plurality of regions, based on the pixel value of the object pixel and a relationship between pixel values of the pixels of the high-resolution image corresponding to the object pixel; and creating a corrected band image that holds a pixel value of light on the object band image at the pixel position of the reference band image, from the determined pixel value of each sub-region and the position difference.

An image processing apparatus processes image data to be used in a printing apparatus configured to perform forward and backward scan printing by using a print head in which nozzle arrays corresponding to multiple colors are aligned. The image processing apparatus includes: a setting unit configured to set a first control parameter in a case where image data to be processed does not include a line portion and to set a second control parameter in a case where the image data to be processed includes a line portion, the second parameter being different from the first control parameter; and a processing unit configured to perform, for the image data to be processed, processing to suppress a difference between a color printed in a forward scan and a color printed in a backward scan based on the control parameter set by the setting unit.