Scanning apparatus having image correction funciton

Abstract

A scanning apparatus includes a scanning head that scans an image of a document positioned on a stage glass, but varying in its distance therefrom. A boundary line is detected to determine an amount of skew therein. A skew line is compared with an established reference line, and a correction factor is calculated based on the result of the comparison. The original image processed to map the boundary line to the reference line and image data inside of the boundary line is similarly mapped based on the calculated correction factor. Beneficially, skews of an image produced when a thick book is scanned can be corrected simply.

1 . A scanning apparatus comprising:
 a stage glass on which a document is positioned;   a scanning head which scans an image of the document while translating below the stage glass;   an image processing part which processes image data produced by the scanning head;   a boundary line detecting part which determines a correction region including a skew line;   a correction region setting part which determines a correction region including a skew line; and   a controller which sets at least one region of the image as the correction region whether a folding point is detected, if the skew line in the boundary line is detected by the boundary line detecting part, compares the skew line with a predetermined reference line which is a line that extends a straight line portion of the boundary line across a folding line, calculates a correction factor corresponding to the correction region based on a result of the comparison, and controls the image processing part to correct the skew line and the image data enclosed by the boundary line based on the calculated correction factor.   
     
     
         2 . The scanning apparatus according to  claim 1 , wherein the correction region setting part sets four regions as the correction in the image of the document around the folding line and a predetermined axis which is orthogonal to the folding line. 
     
     
         3 . The scanning apparatus according to  claim 2 , wherein the folding point comprises a top folding point and a bottom folding point, and the region of the image comprises a right top region, a right bottom region, a left top region and a left bottom region,
 wherein the controller sets the right top region and the left top region as the correction regions if the top folding point is detected, and sets the right bottom region and the left bottom region as the correction regions if the bottom folding point is detected.   
     
     
         4 . The scanning apparatus according to  claim 2 , wherein the correction factor corresponds to each of the correction region. 
     
     
         5 . The scanning apparatus according to  claim 1 , wherein the correction factor is determined by a ratio of a distance between the predetermined axis and points on a first boundary line including the skew line. 
     
     
         6 . The scanning apparatus according to  claim 5 , wherein the correction factor has a plurality of values respectively assigned according to a distance between the first boundary line including the skew line and the corresponding reference line. 
     
     
         7 . The scanning apparatus according to according to  claim 1 , wherein the controller controls the image processing part to map a coordinate of the skew line onto a coordinate of the reference line based on the correction factor. 
     
     
         8 . The scanning apparatus according to  claim 1 , further comprising:
 an image forming part for outputting the image,   wherein the controller controls the image forming part to output the image processed by the image processing part.   
     
     
         9 . The scanning apparatus according to  claim 1 , further comprising a folding line detecting part which detects folding points corresponding to points at which the document is furthest removed from the stage glass. 
     
     
         10 . The scanning apparatus according to  claim 9 , wherein the boundary line detecting part detects the boundary line of a focused data of the image and the folding line detecting part determines the folding points as being a predetermined distance from an opposite boundary lines of the focused data. 
     
     
         11 . An image processing method of a scanning apparatus comprising a stage glass on which a document is positioned and a scanning head which scans an image of the document while translating below the stage glass, comprising:
 detecting a boundary line of the image;   detecting a skew line in the boundary line;   setting at least one region of the image as a correction region including the skew line;   comparing the skew line with a predetermined reference line which is a line that extends a straight line portion of the boundary line across a folding line;   calculating a correction factor corresponding to the correction region based on a result of the comparison; and   correcting the skew line and the image data enclosed by the boundary line based on the calculated correction factor.   
     
     
         12 . The method according to  claim 11 , wherein the setting at least one region of the image comprises setting four regions as the correction in the image of the document around the folding line and a predetermined axis which is orthogonal to the folding line. 
     
     
         13 . The method according to  claim 12 , wherein the folding point comprises a top folding point and a bottom folding point, and the region of the image comprises a right top region, a right bottom region, a left top region and a left bottom region,
 wherein the setting at least one region of the image setting the right top region and the left top region as the correction regions if the top folding point is detected and the right bottom region and setting the left bottom region as the correction regions if the bottom folding point is detected.   
     
     
         14 . The method according to  claim 12 , wherein the correction factor corresponds to each of the correction region. 
     
     
         15 . The method according to  claim 11 , wherein the correction factor is determined by a ratio of a distance between the predetermined axis and points on a first boundary line including the skew line. 
     
     
         16 . The method according to  claim 15 , wherein the correction factor has a plurality of values respectively assigned according to a distance between the first boundary line including the skew line and the corresponding reference line. 
     
     
         17 . The method according to  claim 11 , wherein the correcting the skew line and the image data comprising mapping a coordinate of the skew line onto a coordinate of the reference line based on the correction factor. 
     
     
         18 . The method according to  claim 11 , further comprising outputting the corrected image data by an image forming part. 
     
     
         19 . The method according to  claim 11 , further comprising detecting folding points corresponding to points at which the document is furthest removed from the stage glass. 
     
     
         20 . The method according to  claim 19 , wherein detecting the boundary line comprises detecting the boundary line of a focused data of the image and the detecting folding points comprises determining the folding points as being a predetermined distance from an opposite boundary lines of the focused data.