Electronic image registration for a scanner

Abstract

A system electronically registers an image on an input document. The system includes a scanner for generating an image data stream representing an electronic image of the image on the input document and an edge detecting circuit for detecting edge data within the image data stream A circuit detects a first corner of a leading edge of the input document based on the detected edge data and for establishing a first coordinate value therefrom and a second corner of a leading edge of the input document based on the detected edge data and for establishing a second coordinate value therefrom. The system further determines a minimum and maximum location for a leading edge of the scanned document and determines a minimum and maximum location for a trailing edge of the scanned document. An image window is generated representing valid image data to processed and rendered based on the minimum and maximum location for a leading edge of the scanned document, the minimum and maximum location for a trailing edge of the scanned document, the first coordinate value, and the second coordinate value.

What is Claimed is:  
     
         1 . A system for electronically registering an image on an input document, comprising: 
 scanning means for generating an image data stream representing an electronic image of the image on the input document;    edge detecting means, operatively connected to said scanning means, for detecting edge data within the image data stream;    first corner detecting means, operatively connected to said edge detecting means, for detecting a first corner of a leading edge of the input document based on the detected edge data and for establishing a first coordinate value therefrom;    second corner detecting means, operatively connected to said edge detecting means, for detecting a second corner of a leading edge of the input document based on the detected edge data and for establishing a second coordinate value therefrom;    edge range determining means for determining a minimum and maximum location for a leading edge of the scanned document and for determining a minimum and maximum location for a trailing edge of the scanned document; and    window means for generating an image window representing valid image data to processed and rendered based on said minimum and maximum location for a leading edge of the scanned document, said minimum and maximum location for a trailing edge of the scanned document, said first coordinate value, and said second coordinate value.    
     
     
         2 . The system as claimed in    claim 1   , wherein said first corner detecting means establishes the first coordinate value as being equal to the coordinate value of the detected corner when the first corner is detected within a predetermined number of scanlines.  
     
     
         3 . The system as claimed in    claim 1   , wherein said first corner detecting means establishes the first coordinate value as being equal to the coordinate value of the detected corner when the first corner is detected within a predetermined pixels of a nominal center value.  
     
     
         4 . The system as claimed in    claim 1   , wherein said window means creates a scanning window which encloses all four corners of the document being scanned.  
     
     
         5 . The system as claimed in    claim 1   , wherein said window means creates a scanning window which is within all four corners of the document being scanned.  
     
     
         6 . A method for electronically registering an image on an input document, comprising the steps of: 
 (a) generating an image data stream representing an electronic image of the image on the input document;    (b) detecting edge data within the image data stream;    (c) detecting a first corner of a leading edge of the input document based on the detected edge data and for establishing a first coordinate value therefrom;    (d) detecting a second corner of a leading edge of the input document based on the detected edge data and for establishing a second coordinate value therefrom;    (e) determining a minimum and maximum location for a leading edge of the scanned document;    (f) determining a minimum and maximum location for a trailing edge of the scanned document; and    (g) generating an image window representing valid image data to processed and rendered based on the minimum and maximum location for a leading edge of the scanned document, the minimum and maximum location for a trailing edge of the scanned document, the first coordinate value, and the second coordinate value.    
     
     
         7 . The method as claimed in    claim 6   , wherein said step (c) establishes the first coordinate value as being equal to the coordinate value of the detected corner when the first corner is detected within a predetermined number of scanlines.  
     
     
         8 . The method as claimed in    claim 6   , wherein said step (c) establishes the first coordinate value as being equal to the coordinate value of the detected corner when the first corner is detected within a predetermined pixels of a nominal center value.  
     
     
         9 . The method as claimed in    claim 6   , wherein said step (g) creates a scanning window which encloses all four corners of the document being scanned.  
     
     
         10 . The method as claimed in    claim 6   , wherein said step (g) creates a scanning window which is within all four corners of the document being scanned.