Image compensation in regions of low image contrast

Abstract

To compensate an image, a profile thereof is obtained from pixel values in a marginal area of the image. A background value of the image determined from the profile and correction to the image is performed in accordance with the background value and the profile.

1 . An image compensation apparatus, comprising:
 a memory part to store a copy of an image as a plurality of image pixels, the stored image copy including background image pixels having a background value corresponding to a background characteristic of the image; and   an image processing part to determine the background value from at least one area of the image pixels and to compensate the image pixels in a region of any copy of the image in which the background image pixels therein have a value of the background characteristic other than the background value.   
     
     
         2 . The image compensation apparatus according to  claim 1 , wherein the at least one area of image pixels from which the background value is determined includes a plurality of the background image pixels having the value other than the background value. 
     
     
         3 . The image compensation apparatus according to  claim 2 , wherein the image processing part determines a relationship of the value of the background characteristic other than the background value in one area of the image pixels from which the background value is determined and the value of the background characteristic other than the background value in another area of the image pixels from which the background value is determined. 
     
     
         4 . The image compensation apparatus according to  claim 3 , wherein the image processing part scales the background characteristic of the image pixels in the region of any copy of the image by the background value and a value determined from the relationship of the value of the background characteristic other than the background value in the area of the image pixels and the other area of the image pixels. 
     
     
         5 . The image compensation apparatus according to  claim 4 , wherein the image processing part linearly interpolates the relationship of the value of the background characteristic other than the background value in the area of the image pixels and the other area of the image pixels to determine the value thereof at a location of an image pixel being scaled. 
     
     
         6 . The image compensation apparatus according to  claim 1 , wherein the image pixels of the copy of the image are stored in the memory part as a plurality of scan lines and a plurality of image rows. 
     
     
         7 . The image compensation apparatus according to  claim 6 , wherein the image processing part determines the background value from the image rows of the at least one area of the image pixels and compensates the image pixels of each of the scan lines in the region of the any copy of the image. 
     
     
         8 . The image compensation apparatus according to  claim 7 , further comprising:
 a scanning part to digitize the image into the image pixels, the scanning part further to provide each of the scan lines of another copy of the image to the image processing part to compensate the image pixels thereof.   
     
     
         9 . The image compensation apparatus according to  claim 8 , wherein the scan lines of the other copy of the image are compensated individually upon receipt thereof from the scanning part. 
     
     
         10 . The image compensation apparatus according to  claim 8 , wherein a scanning resolution of the copy of the image is less than the scanning resolution of the other copy of the image. 
     
     
         11 . The image compensation apparatus according to  claim 8 , wherein the scanning part scans the image on a scan plane thereof and the region of the any copy of the image in which the background image pixels therein have the value of the background characteristic other than the background value is a region of the image removed from the scan plane. 
     
     
         12 . The image compensation apparatus according to  claim 1 , wherein image processing part determines the background value from a histogram of values of the image pixels in the at least one area of the image. 
     
     
         13 . The image compensation apparatus according to  claim 1 , wherein the image processing part determines the background value from a histogram of values of the image pixel in more than one area of the image. 
     
     
         14 . The image compensation apparatus according to  claim 13 , wherein the more than one area from which the background value is determined is a first marginal area of the image and a second marginal area of the image. 
     
     
         15 . An image compensation method, comprising:
 storing a copy of an image as a plurality of image pixels, the stored image copy including background image pixels having a first background value corresponding to a background characteristic of the image;   determining the first background value from at least one area of the image pixels; and   compensating the image pixels in a region of any copy of the image in which the background image pixels therein have a value of the background characteristic other than the first background value.   
     
     
         16 . The image compensation method according to  claim 15 , further comprising:
 determining a second background value from a relationship of the value of the background characteristic other than the first background value in one area of the image pixels from which the first background value is determined and the value of the background characteristic other than the first background value in another area of the image pixels from which the first background value is determined.   
     
     
         17 . The image compensation method according to  claim 16 , wherein the compensating the image pixels includes:
 scaling the background characteristic of an image pixel in the region of the any copy of the image by the first background value and the second background.   
     
     
         18 . The image compensation method according to  claim 17 , wherein the second background value determining includes:
 linearly interpolating the relationship of the value of the background characteristic other than the first background value in the area of the image pixels and the other area of image pixels in accordance with a location of an image pixel being scaled.   
     
     
         19 . The image compensation method according to  claim 15 , wherein the storing of the copy of the image includes:
 storing the image pixels as a plurality of scan lines and a plurality of image rows.   
     
     
         20 . The image compensation method according to  claim 19 , wherein the determining of the first background value includes:
 determining the first background value from the image rows of the at least one area of image pixels.   
     
     
         21 . The image compensation method according to  claim 20 , wherein the compensating the image pixels includes:
 compensating each of the scan lines in the region of the any copy of the image.   
     
     
         22 . The image compensation method according to  claim 21 , wherein the compensating of the scan lines includes:
 compensating the scan lines individually upon receipt thereof.   
     
     
         23 . The image compensation method according to  claim 15 , wherein the determining the first background value includes:
 determining the first background value from a histogram of image pixel values in the at least one area of the image.   
     
     
         24 . The image compensation method according to  claim 15 , wherein the determining the first background value includes:
 determining the first background data from a histogram of image pixel values in more than one area of the image.