An image reading apparatus includes: a conveyance unit configured to convey the original; an image reading unit configured to read an image of the original conveyed by the conveyance unit by using a reading sensor to generate image data which represents a reading result; at least one processor configured to: detect a streak image in an image represented by the image data based on the image data; determine a content area in the image represented by the image data, the content area being an area where content is printed, and perform correction processing for removing the streak image by correcting the image data; wherein the at least one processor is configured to be operable in a first reading mode in which the correction processing is performed to image data corresponding to the streak image in an area outside the content area.

An image reading apparatus includes an original tray on which an original is to be stacked; a conveyance unit configured to convey the original stacked on the original tray; a reading unit including a reading sensor having a light receiving element to receive light of a first color and a light receiving element to receive light of a second color that is different from the first color, wherein the reading unit is configured to read an image of the original conveyed by the conveyance unit by using the reading sensor to generate image data which represents a reading result of the reading unit; at least one processor configured to: determine a first abnormal position which is a position in a first direction of an abnormal pixel of the first color in the image represented by the image data, wherein, in the image represented by the image data.

An image reading apparatus includes a conveyance unit configured to convey an original; a reading unit comprising a reading sensor, the reading sensor having a light receiving element to receive light of a first color and a light receiving element to receive light of a second color that is different from the first color, wherein the reading unit is configured to read an image of the original conveyed by the conveyance unit by using the reading sensor to generate image data which represents a reading result of the reading unit; at least one processor configured to: determine a first abnormal position that is a position in a first direction of an abnormal pixel of the first color in an image represented by the image data.

An image reading apparatus acquires first image data of a background portion stored in advance and read by a reading unit, acquires second image data by reading the background portion, generates third image data by increasing resolution of the first image data and fourth image data by increasing resolution of the second image data, detects an amount of shift of an image sensor relative to a lens array in a predetermined direction by shifting a specific pixel range of the fourth image data relative to the third image data and comparing the specific pixel range with the third image data, and compares fifth image data obtained by shifting the fourth image data in accordance with the shift amount with the third image data, so as to determine whether each of pixels included in the fifth image data is a defective pixel having an abnormal value.

In an example method, an image of a printed document is descreened. The descreened image is separated into blocks. A smooth area of the descreened image is selected based on an averaging of localized color distance values of pixels in each of the blocks. A streak in a block of the smooth area is detected in response to detecting that a magnitude of a color distance projection of the block exceeds a threshold value.

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 reading device includes a reading unit that reads a document sheet and a reading standard surface and outputs read values corresponding to pixels arranged in a main scan direction, a control unit that processes the read values, and a storage unit storing information to be referenced by the control unit. In the storage unit, first data that is read values of the reading standard surface and serves as standards, and second data on ranges of variation, based on a change in a temperature, in the read values are stored. The control unit determines, based on the first data and the second data read from the storage unit and third data obtained by reading the reading standard surface after an acquisition of the first data, whether an abnormality exists in the pixels.

An image reading apparatus acquires first image data of a background portion stored in advance and read by a reading unit, acquires second image data by reading the background portion, generates third image data by increasing resolution of the first image data and fourth image data by increasing resolution of the second image data, detects an amount of shift of an image sensor relative to a lens array in a predetermined direction by shifting a specific pixel range of the fourth image data relative to the third image data and comparing the specific pixel range with the third image data, and compares fifth image data obtained by shifting the fourth image data in accordance with the shift amount with the third image data, so as to determine whether each of pixels included in the fifth image data is a defective pixel having an abnormal value.

An apparatus corrects a piece of pixel data of a first color of which abnormal pixel is detected in a first color without correcting a piece of pixel data of a second color of which abnormal pixel is not detected in the second color, in the generated pieces of pixel data in a case where the abnormal pixel is a pixel other than a pixel located at an edge portion, and corrects a plurality of pieces of pixel data of all colors at a position where the abnormal pixel is detected in the generated plurality of pieces of pixel data in a case where the detected abnormal pixel is the pixel located at the edge portion.

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.