# US 2017/0257495 A1 · Image reading apparatus, control method, and computer-readable, non-transitory medium > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0257495 A1 - Document ID: US20170257495A1 - Status: Published application - Kind: A1 - Application number: 15/178,139 - Filed: 2016-06-09 - Published: 2017-09-07 - Earliest claimed: 2016-03-03 - Assignees: Pfu Limited - Applicants: Pfu Limited - Inventors: Shingo Kanaya - Web page: https://patentgrep.com/patent/US20170257495A1 ## CPC - H04N 1/00037: {Detecting, i.e. determining the occurrence of a predetermined state (H04N1/00031 takes precedence)} - H04N 1/00013: {Reading apparatus} - H04N 1/00092: {relating to the original or to the reproducing medium, e.g. imperfections or dirt (detecting properties of a sheet H04N1/00681)} - H04N 1/0057: {Conveying sheets before or after scanning (arrangements for conveying sheets as part of the scanning operation H04N1/04 and subgroups)} - H04N 1/00615: {Guiding elements, e.g. plates} - H04N 1/00702: {Position} - H04N 1/02815: {Means for illuminating the original, not specific to a particular type of pick-up head} - H04N 1/2032: {of two pictures corresponding to two sides of a single medium (refeeding a sheet for double-sided scanning H04N1/00572)} - H04N 1/4097: {Removing errors due external factors, e.g. dust, scratches} - H04N 2201/0081: Image reader (H04N2201/0091 - H04N2201/0094 take precedence) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image reading apparatus includes an image capturing module, a reference member, a light source for emitting light to the reference member, a foreign object determining module for determining whether or not a foreign object appears in a specific image, and a position determining module for determining whether the foreign object exists on the image capturing module side or on the reference member side, based on an absolute value of a difference between a gradation value in a region included in two images and corresponding to a region where the foreign object appears when the foreign object appears in the specific image. One image is an image of the reference member captured under illumination of light with a first light quantity from the light source, and other image is an image of the reference member captured under illumination of light with a second light quantity from the light source. ## Claims ### Claim 1 An image reading apparatus comprising: an image capturing module for capturing a first image and a second image; a reference member provided at a position facing the image capturing module; a light source for emitting light to the reference member; a foreign object determining module for determining whether or not a foreign object appears in a specific image captured by the image capturing module; and a position determining module for determining whether the foreign object exists on the image capturing module side or on the reference member side, based on an absolute value of a difference between a gradation value in a region included in the first image and corresponding to a region where the foreign object appears and a gradation value in a region included in the second image and corresponding to the region where the foreign object appears when the foreign object appears in the specific image; wherein the first image is an image of the reference member captured under illumination of light with a first light quantity from the light source, and the second image is an image of the reference member captured under illumination of light with a second light quantity from the light source, the second light quantity being different from the first light quantity. ### Claim 2 (depends on 1) The image reading apparatus according to claim 1, wherein when the absolute value of the difference is equal to or larger than a predetermined threshold, the position determining module determines that the foreign object exists on the image capturing module side, and when the absolute value of the difference is smaller than the predetermined threshold, the position determining module determines that the foreign object exists on the reference member side. ### Claim 3 (depends on 1) The image reading apparatus according to claim 1, wherein the image capturing module further captures a reference image for correcting a document image obtained by capturing a document, and the image reading apparatus further comprises a reference image correcting module for not correcting the reference image when the foreign object exists on the image capturing module side, and correcting the reference image when the foreign object exists on the reference member side. ### Claim 4 (depends on 3) The image reading apparatus according to claim 3, wherein the position determining module determines whether or not the absolute value of the difference is equal to or larger than the predetermined threshold, for each of a red component, a green component, and a blue component, and the reference image correcting module corrects a color component whose absolute value of the difference is smaller than the predetermined threshold in the reference image. ### Claim 5 (depends on 3) The image reading apparatus according to claim 3, wherein the position determining module determines whether or not the absolute value of the difference is equal to or larger than the predetermined threshold, for each of a red component, a green component, and a blue component, and the reference image correcting module corrects the reference image only when the absolute value of the difference is smaller than the predetermined threshold for all of the components of the red component, the green component, and the blue component. ### Claim 6 (depends on 3) The image reading apparatus according to claim 3, further comprising a receiving module for receiving setting that indicates which of a single color and a plurality of colors is used to capture the document, wherein the position determining module determines whether the foreign object exists on the image capturing module side or on the reference member side, based on one of the red component, the green component, or the blue component when the receiving module receives setting that indicates that a single color is used to capture the document, and the position determining module determines whether the foreign object exists on the image capturing module side or on the reference member side, based on all the color components of the red component, the green component, and the blue component when the receiving module receives setting that indicates that a plurality of colors is used to capture the document. ### Claim 7 A control method of an image reading apparatus comprising an image capturing module for capturing a first image and a second image, a reference member provided at a position facing the image capturing module, and a light source that for emitting light to the reference member; the method comprising: determining whether or not a foreign object appears in a specific image captured by the image capturing module; and determining whether the foreign object exists on the image capturing module side or on the reference member side, based on an absolute value of a difference between a gradation value in a region included in the first image and corresponding to a region where the foreign object appears and a gradation value in a region included in the second image and corresponding to the region where the foreign object appears when the foreign object appears in the specific image; wherein the first image is an image of the reference member captured under illumination of light with a first light quantity from the light source, and the second image is an image of the reference member captured under illumination of light with a second light quantity from the light source, the second light quantity being different from the first light quantity. ### Claim 8 A computer-readable, non-transitory medium storing a computer program, wherein the computer program causes an image reading apparatus comprising an image capturing module for capturing a first image and a second image, a reference member provided at a position facing the image capturing module, and a light source for emitting light to the reference member to execute a process, the process comprising: determining whether or not a foreign object appears in a specific image captured by the image capturing module; and determining whether the foreign object exists on the image capturing module side or on the reference member side, based on an absolute value of a difference between a gradation value in a region included in the first image and corresponding to a region where the foreign object appears and a gradation value in a region included in the second image and corresponding to the region where the foreign object appears when the foreign object appears in the specific image; wherein the first image is an image of the reference member captured under illumination of light with a first light quantity from the light source, and the second image is an image of the reference member captured under illumination of light with a second light quantity from the light source, the second light quantity being different from the first light quantity.