Image correction method

Abstract

An image correction method is provided. First, scan an all-white document and form a scanned image including a plurality of image pixels with each of them having a gray level value. Next, gather these gray level values statistically such that each of them has an image pixel quantity. Then the maximum gray level value and the minimum gray level value are selected and a middle gray level value is obtained accordingly. Following that, determine whether the reference gray level value is greater or smaller than the middle gray level value according to the document, select the gray level values from within the interval of (the reference gray level value ± a gray level value), and weight average the selected gray level values according to these selected gray level values and their corresponding image pixel quantities to obtain a corrected gray level value.

1 - 20 . (canceled)  
     
     
         21 . An image correction method for use with a scanned document having a plurality of image pixels with each of the image pixels having a gray level value, comprising: 
 calculating a middle gray level value;    selecting a reference gray level value;    determining whether the reference gray level value is greater or smaller than the middle gray level value; and    selecting the gray level values from within an interval of (the reference gray level value±a gray level value), and weight averaging the selected gray level values according to the selected gray level values to obtain a corrected gray level value.    
     
     
         22 . The image correction method of  claim 21  wherein the middle gray level value equals half or nearly half of a sum of a maximum gray level value and a minimum gray level value.  
     
     
         23 . The image correction method of  claim 21  wherein the middle gray level value equals half or nearly half of a difference between a maximum gray level value and a minimum gray level value.  
     
     
         24 . An image corrector for use with a scanned document having a plurality of image pixels with each of the image pixels having a gray level value, comprising: 
 means for calculating a middle gray level value;    means for selecting a reference gray level value;    means for determining whether the reference gray level value is greater or smaller than the middle gray level value; and    means for selecting the gray level values from within an interval of (the reference gray level value±a gray level value), and weight averaging the selected gray level values according to the selected gray level values to obtain a corrected gray level value.    
     
     
         25 . The image corrector of  claim 24  wherein the middle gray level value equals half or nearly half of a sum of a maximum gray level value and a minimum gray level value.  
     
     
         26 . The image corrector of  claim 24  wherein the middle gray level value equals half or nearly half of a difference between a maximum gray level value and a minimum gray level value.  
     
     
         27 . A method of filtering image blemishes, comprising: 
 calculating a middle gray level value of a scanned document having a plurality of image pixels with one or more of the image pixels having a gray level value;    selecting a reference gray level value that is a gray level value common to most or nearly most image pixels;    determining whether the reference gray level value is greater or smaller than the middle gray level value; and    selecting the gray level values from within an interval of (the reference gray level value ±a gray level value), and weight averaging the selected gray level values according to the selected gray level values to obtain a corrected gray level value.    
     
     
         28 . An image correction method, comprising: 
 calculating a middle gray level value from a maximum gray level value and a minimum or nearly minimum gray level value of a scanned document having a plurality of image pixels with one or more of the image pixels having a gray level value and one or more gray level value having an image pixel quantity;    selecting a reference gray level value, wherein the reference gray level value has a largest or nearly largest image pixel quantity;    determining whether the reference gray level value is greater or smaller than the middle gray level value; and    selecting the gray level values from within an interval of (the reference gray level value±a gray level value), and weight averaging the selected gray level values according to the selected gray level values and their corresponding image pixel quantities to obtain a corrected gray level value.    
     
     
         29 . The image correction method of  claim 28  further comprising forming a profile of the gray level values according to the gray level values and their corresponding image pixel quantities.  
     
     
         30 . The image correction method of  claim 28  wherein the middle gray level value equals half or nearly half of a sum of the maximum gray level value and the minimum gray level value.  
     
     
         31 . The image correction method of  claim 28  wherein the middle gray level value equals half or nearly half of a difference between the maximum gray level value and the minimum gray level value.  
     
     
         32 . A scanner having an image corrector that corrects images by: 
 calculating a middle gray level value;    selecting a reference gray level value;    determining whether the reference gray level value is greater or smaller than the middle gray level value; and    selecting the gray level values from within an interval of (the reference gray level value±a gray level value), and weight averaging the selected gray level values according to the selected gray level values to obtain a corrected gray level value.    
     
     
         33 . The scanner of  claim 32  wherein the middle gray level value equals half or nearly half of a sum of a maximum gray level value and a minimum gray level value.  
     
     
         34 . The scanner of  claim 32  wherein the middle gray level value equals half or nearly half of the difference between a maximum gray level value and a minimum gray level value.  
     
     
         35 . The scanner of  claim 32  wherein the reference gray level value is a gray level value common to most or nearly most image pixels.  
     
     
         36 . An image correction method for use with a scanned document having a plurality of image pixels with the image pixels having a gray level value, comprising: 
 calculating a middle gray level value;    selecting a reference gray level value by determining which gray level value is common to most or nearly most image pixels;    comparing the reference gray level value to the middle gray level value;    selecting gray level values from within an interval of (the reference gray level value±a gray level value); and    calculating a corrected gray level value from weight averaging the selected gray level values according to the reference gray level value.    
     
     
         37 . The image correction method of  claim 36  wherein the middle gray level value equals half or nearly half of a sum of a maximum gray level value and a minimum gray level value.  
     
     
         38 . The image correction method of  claim 36  wherein the middle gray level value equals half or nearly half of the difference between a maximum gray level value and a minimum gray level value.  
     
     
         39 . A scanner with an image corrector comprising: 
 means for calculating a middle gray level value of a scanned document having a plurality of image pixels with one or more of the image pixels having a gray level value and one or more gray level value having an image pixel quantity;    means for selecting a reference gray level value, wherein the reference gray level value has a largest or nearly largest image pixel quantity;    means for determining whether the reference gray level value is greater or smaller than the middle gray level value; and    means for selecting the gray level values from within an interval of (the reference gray level value±a gray level value); and    means for calculating a corrected gray level value by weight averaging the selected gray level values according to the selected gray level values and their corresponding image pixel quantities to obtain a corrected gray level value.