System and method for filtering and binarization of images in the presence of specular noise

Abstract

In order to render information contained in images more detectable in the presence of noise, the present invention discloses a system and method to binarize the images in the presence of noise. The method of this invention comprises the steps of applying a dynamic range reducing filter to the digitized image values, obtaining a range reduced image; applying an edge detecting filter to the range reduced image, obtaining a filtered image; and then, adaptively binarizing the digitized image utilizing the corresponding filtered image to obtain an adaptive threshold.

1 . A computer program product comprising: 
 a computer usable medium having computer readable code embodied therein for decoding a image in the presence of noise, said image being a digitized image comprising pixels, each said pixel having a corresponding digitized image value, said code causing a computer system to: 
 apply a non linear dynamic range reducing filter to the digitized image value of each said pixel;  
 obtain a range reduced image comprising range reduced image pixels, each of the range reduced image pixels having a corresponding range reduced image pixel value;  
 apply an edge detecting filter to the range reduced image; and  
 obtain, by applying said edge detecting filter, a filtered image comprising filtered image pixels, each of the filtered image pixels having a corresponding filtered image pixel value;  
 adaptively binarize the digitized image utilizing an adaptive threshold obtained from the filtered image pixel value.  
   
   
   
       2 . The computer program product of  claim 1  where, in the computer readable code that causes the computer system to apply an edge detecting filter to the digitized bar code image, the edge detecting filter comprises a Hildreth-Marr filter times a constant.  
   
   
       3 . The computer program product of  claim 1  where, in the computer readable code that causes the computer system to apply a dynamic range reducing filter to the digitized image, the dynamic range reducing filter comprises a filter producing a range reduced image pixel value equal to a base ten logarithm, said logarithm having an argument equal to one plus the digitized image pixel value.  
   
   
       4 . The computer program product of  claim 1  where, the computer readable code that causes the computer system to adaptively binarize the digitized image, further causes the computer system to compare the digitized image value to the filtered image pixel value at each pixel.