Image rotation with substantially no aliasing error

Abstract

A system, method and program product for rotating a first image in an image buffer such that the resulting, rotated image is substantially free of an aliasing error, i.e., broken lines, stair stepped edges, etc., is dislosed. An algorithm is applied to the first image that uses weighted sums of data points of the first image to create the rotated image. The weighting is based on the skew angle and data point location of the first image. The resulting rotated image also has a reduced data storage space requirement compared to rotated images created by prior art techniques.

1 . A method of rotating a first image in an image buffer, the method comprising the steps of: 
 extracting first image from the image buffer; and    creating a rotated image that is substantially free of aliasing error using weighted sums of a plurality of data points of the first image that represent pixel data values of the first image to get a pixel data value of the rotated image, wherein weighting depends on a skew angle of the first image and data point location in the first image.    
   
   
       2 . The method of  claim 1 , wherein the first image is of a document, and the first image data is created in the image buffer by the step of scanning the document.  
   
   
       3 . The method of  claim 1 , further comprising the step of storing the first image data in a database.  
   
   
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       10 . A system for rotating an initial image stored in an image buffer, the system comprising: 
 an image rotation module configured to rotate the initial image to create a rotated image by using weighted sums of a plurality of data points of the initial image that represent pixel data values of the initial image to get a pixel data value of the rotated image, wherein the weighting depends on a skew angle of the initial image and data point location in the initial image.    
   
   
       11 . The system of  claim 10 , wherein the data points of the initial image are in adjacent rows of the image buffer.  
   
   
       12 . The system of  claim 11 , wherein a pair of data points are used from each of the adjacent rows of the image buffer.  
   
   
       13 . The system of  claim 10 , further comprising an image generation module configured to create the initial image.  
   
   
       14 . The system of  claim 13 , further comprising a scanner for supplying data to the image generation module.  
   
   
       15 . The system of  claim 10 , further comprising a database configured to store initial image data.  
   
   
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       22 . A workstation comprising the system for rotating an initial image stored in an image buffer of  claim 10 .  
   
   
       23 . A computer program product comprising a computer usable medium having computer readable program code embodied therein for processing a first image in an image buffer, the computer program product comprising: 
 program code configured to rotate the first image to create a rotated image by using weighted sums of a plurality of data points of the first image that represent pixel data values of the first image to get a pixel data value of the rotated image, wherein the weighting depends on a skew angle of the first image and data point location in the first image.    
   
   
       24 . (canceled)  
   
   
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       26 . A system for rotating an initial image stored in an image buffer, the system comprising: 
 an image rotation module configured to rotate the initial image to create a rotated image that is substantially free of an aliasing error using weighted sums of data points of the initial image that represent pixel data values of the initial image to get a pixel data value of the rotated image, wherein weighting depends on a skew angle of the initial image and data point location in the initial image and is implemented in ⅛th increments.    
   
   
       27 . (canceled)