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US 12,743,786 B2Granted
Image processing device, image forming apparatus, and edge detection method
AssigneeRicoh Company, Ltd.
InventorAtsushi Yoshida
Life of this patent
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Abstract
An image processing device includes a processing circuit, a detection circuit, a setting circuit, and a decision circuit. The processing circuit obtains, from image data of a document read by a reading device, a value relating to a difference between pixel values of adjacent pixels in a direction from a background portion to a document portion in the image data. The detection circuit searches for a pixel in the direction and detects an edge, which indicates a boundary between the background portion and the document portion, based on the value relating to the difference. The setting circuit sets the detected edge as a first edge or a second edge. The decision circuit decides the second edge as a document edge of the document.
Claims16
An image processing device comprising:
- a processing circuit configured to obtain, from image data of a document read by a reading device, a difference between pixel values of adjacent pixels in a sub-scanning direction from a background portion to a document portion in the image data, wherein the processing circuit is configured to obtain a differential amount of each of the pixel values as the difference;
- a detection circuit configured to search for a pixel in the sub-scanning direction and detect an edge based on the difference to obtain a detected edge, the detected edge indicating a boundary between the background portion and the document portion;
- a setting circuit configured to,
- in response to the detection circuit firstly detecting the edge of a darkening change, set the detected edge as a first edge, wherein, in response to the differential amount corresponding to a pixel value of a target pixel being equal to or less than a first threshold value, the detection circuit is configured to detect the target pixel as the edge of the darkening change;
- in response to the detection circuit detecting the edge of a brightening change before detecting the first edge, set the detected edge as a second edge, wherein, in response to the differential amount corresponding to the pixel value of the target pixel being equal to or greater than a second threshold value greater than the first threshold value, the detection circuit is configured to detect the target pixel as the edge of the brightening change;
- and
- in response to the detection circuit detecting the edge of the darkening change or the edge of the brightening change after detecting the first edge, set the detected edge as the second edge;
- and
- a decision circuit configured to decide the second edge as a document edge of the document,
- wherein the setting circuit is configured to,
- after the detection circuit detects the first edge, determine whether a distance between a position of the first edge and a position of the target pixel is less than a third threshold value;
- and
- in response to the distance being equal to or greater than the third threshold value, set the first edge as the second edge.
10 more elements
An edge detection method comprising:
- obtaining, from image data of a document read by a reading device, a difference between pixel values of adjacent pixels in a sub-scanning direction from a background portion to a document portion in the image data, wherein the obtaining obtains a differential amount of each of the pixel values as the difference;
- searching for a pixel in the sub-scanning direction and detecting an edge based on the difference to obtain a detected edge, the detected edge indicating a boundary between the background portion and the document portion;
- setting the detected edge as a first edge or a second edge, the setting including,
- in response to the edge of a darkening change being firstly detected, setting the detected edge as the first edge, wherein, in response to the differential amount corresponding to a pixel value of a target pixel being equal to or less than a first threshold value, the detecting detects the target pixel as the edge of the darkening change;
- in response to the edge of a brightening change being detected before the first edge is detected, setting the detected edge as the second edge, wherein, in response to the differential amount corresponding to the pixel value of the target pixel being equal to or greater than a second threshold value greater than the first threshold value, the detecting detects the target pixel as the edge of the brightening change;
- and
- in response to the edge of the darkening change or the edge of the brightening change being detected after the first edge is detected, setting the detected edge as the second edge;
- and
- deciding the second edge as a document edge of the document, wherein the setting includes,
- after the first edge is detected, determining whether a distance between a position of the first edge and a position of the target pixel is less than a third threshold value;
- and
- in response to the distance being equal to or greater than the third threshold value, setting the first edge as the second edge.
9 more elements
Dependencies are inferred from the claim text.