Image scanner and image scanning method

Abstract

An image scanner includes: a lid or a backing sheet as a cover unit on which a pattern is depicted; a sensor unit configured to scan a document between a platen and the cover unit; and an image processing unit configured to set a threshold value using information on a first transmitted pattern of the pattern, obtained through the document, and perform image processing based on the threshold value.

1 . A scan device comprising:
 a scanning unit that scans a document, and   an image processing unit that sets a threshold value based on a brightness obtained at a predetermined location on the document, and removes an image in a processing region having a brightness greater than or equal to the threshold value.   
     
     
         2 . The scan device according to  claim 1 , further comprising
 a cover unit on which a marking is depicted in a location corresponding to the predetermined location.   
     
     
         3 . The scan device according to  claim 2 ,
 wherein a pattern is depicted on the cover unit in the location corresponding to the predetermined location, the pattern including a plurality of the markings.   
     
     
         4 . The scan device according to  claim 2 ,
 wherein the cover unit is one of a lid that contacts a back side of the document in a closed state and a backing sheet layered behind the document.   
     
     
         5 . The scan device according to  claim 1 ,
 wherein the image processing unit sets the threshold value to the brightness obtained at the predetermined location on the document.   
     
     
         6 . The scan device according to  claim 2 ,
 wherein the marking of the cover unit includes a first marking and a second marking less dense than the first marking, and   the image processing unit corrects a brightness of the processing region based on a brightness of the second marking obtained from a result of the scan.   
     
     
         7 . The scan device according to  claim 6 ,
 wherein the image processing unit converts the brightness of the processing region to the brightness of the second marking.   
     
     
         8 . The scan device according to  claim 6 ,
 wherein the image processing unit does not correct the brightness of the processing region when a difference between a brightness of the first marking obtained from the result of the scan and the brightness of the second marking obtained from the result of the scan is less than or equal to a predetermined value.   
     
     
         9 . The scan device according to  claim 2 , further comprising:
 a reference data memory in which reference data representing the marking is stored in advance; and   a detection unit that uses the reference data to detect, in a scanned image obtained from a result of the scan, a specific region including the marking,   wherein the image processing unit sets the threshold value based on a brightness of the specific region detected by the detection unit.   
     
     
         10 . The scan device according to  claim 9 ,
 wherein the detection unit detects an extending portion extending beyond an edge of the document by detecting a portion of the specific region having a brightness lower than a predetermined value, and excludes the extending portion from the specific region, and   the image processing unit removes the extending portion from the scanned image.   
     
     
         11 . A scanning method comprising:
 scanning a document;   setting a threshold value based on a brightness obtained at a predetermined location on the document; and   removing, from a result of the scanning, an image in a processing region having a brightness greater than or equal to the threshold value.   
     
     
         12 . The scanning method according to  claim 11 ,
 wherein in the scanning, a first side of the document is scanned while a cover unit on which a first marking is depicted is in contact with a second side of the document opposite the first side,   the scanning method further comprises obtaining a brightness of the first marking from the result of the scanning,   in the setting, the threshold value is set based on the brightness of the first marking, and   in the removing, show-through appearing in the processing region having a brightness greater than or equal to the threshold value is removed.   
     
     
         13 . The scanning method according to  claim 12 ,
 wherein the cover unit further depicts a second marking less dense than the first marking, and   the scanning method further comprises:   obtaining a brightness of the second marking from the result of the scanning; and   determining whether a difference between the brightness of the first marking and the brightness of the second marking is less than or equal to a predetermined value,   wherein the removing is not performed when the difference is less than or equal to the predetermined value.