# US 10,771,636 B2 · Image processing apparatus for detecting a noise line based on noise pixels in the shadow region > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,771,636 B2 - Document ID: US10771636B2 - Status: Granted - Kind: B2 - Application number: 16/124,098 - Filed: 2018-09-06 - Published: 2019-09-12 - Granted: 2020-09-08 - Earliest claimed: 2018-03-12 - Assignees: Pfu Limited - Applicants: Pfu Limited - Inventors: Takeshi Yokogawa; Kunihiko Ohmi; Kodai Yamane - Web page: https://patentgrep.com/patent/US10771636B2 ## CPC - H04N 1/00029: {Diagnosis, i.e. identifying a problem by comparison with a normal state} - G06V 10/30: Noise filtering - G06V 10/44: Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components - G06V 30/40: Document-oriented image-based pattern recognition - H04N 23/811: {by dust removal, e.g. from surfaces of the image sensor or processing of the image signal output by the electronic image sensor} - H04N 25/63: applied to dark current - H04N 25/67: applied to fixed-pattern noise, e.g. non-uniformity of response - H04N 25/683: by defect estimation performed on the scene signal, e.g. real time or on the fly detection - G06T 2207/10008: from scanner, fax or copier - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract An image processing apparatus includes a processor for acquiring an input image of a document and a periphery of the document, extracting first edge pixels from the input image, detecting a document region based on the first edge pixels, detecting a shadow region from within a predetermined range outside of the document region, extracting noise pixels in the shadow region, detecting the noise pixels, a number of which connected with one another is equal to or more than a predetermined number, as a noise line, and correcting the document region of the input image based on a detection result of the noise line. ## Claims ### Claim 1 An image processing apparatus comprising: a processor for acquiring an input image of a document and a periphery of the document, extracting first edge pixels from the input image, detecting a document region based on the first edge pixels, detecting a shadow region from within a predetermined range outside of the document region, extracting noise pixels in the shadow region, detecting the noise pixels, a number of which connected with one another is equal to or more than a predetermined number, as a noise line, and correcting the document region of the input image based on a detection result of the noise line. ### Claim 2 (depends on 1) The image processing apparatus according to claim 1, wherein the processor extracts, as the noise pixels, pixels where a difference between a gradient value of the shadow region and a gradient value of the noise pixels is equal to or more than a threshold. ### Claim 3 (depends on 1) The image processing apparatus according to claim 1, wherein the processor acquires device information that indicates arrangement of an imaging device and a light source in a device that generates the input image, and determines the predetermined range based on the device information. ### Claim 4 (depends on 1) The image processing apparatus according to claim 1, wherein the processor extracts second edge pixels from within the predetermined range, detects a plurality of line segments based on the second edge pixels, and detects, as the shadow region, a region within a second predetermined range from each of the plurality of line segments. ### Claim 5 (depends on 1) The image processing apparatus according to claim 1, wherein the processor specifies, in the document region, a noise line region corresponding to a noise line detected in the shadow region, determines whether the noise line region overlaps a content based on a difference between a gradient value of the noise line region and a gradient value of peripheral pixels of the noise line region, and changes a method of correcting the noise line region according to a result of the determining whether the noise line region overlaps a content. ### Claim 6 (depends on 5) The image processing apparatus according to claim 5, wherein the processor corrects the noise line region based on the peripheral pixels of the noise line region when the processor determines that the noise line region does not overlap a content. ### Claim 7 (depends on 5) The image processing apparatus according to claim 5, wherein when the processor determines that the noise line region overlaps a content, the processor further determines whether the content is a character, when the processor determines that the content is not a character, the processor does not correct the noise line region, and when the processor determines that the content is a character, the processor corrects the noise line region. ### Claim 8 (depends on 7) The image processing apparatus according to claim 7, wherein when the processor determines that the content is a character, the processor estimates a character overlapping the noise line region from a context of the content and corrects the noise line region based on the estimated character. ### Claim 9 A control method of an image processing apparatus, the method comprising: acquiring an input image of a document and a periphery of the document; extracting first edge pixels from the input image; detecting a document region based on the first edge pixels; detecting a shadow region from within a predetermined range outside of the document region; extracting noise pixels in the shadow region; detecting the noise pixels, a number of which connected with one another is equal to or more than a predetermined number, as a noise line; and correcting the document region of the input image based on a detection result of the noise line. ### Claim 10 A computer-readable, non-transitory medium storing a computer program, wherein the computer program causes an image processing apparatus to execute a process, the process comprising: acquiring an input image of a document and a periphery of the document; extracting first edge pixels from the input image; detecting a document region based on the first edge pixels; detecting a shadow region from within a predetermined range outside of the document region; extracting noise pixels in the shadow region; detecting the noise pixels, a number of which connected with one another is equal to or more than a predetermined number, as a noise line; and correcting the document region of the input image based on a detection result of the noise line.