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Method and apparatus for automatically locating a region of interest in a radiograph

  • US 5,982,916 A
  • Filed: 09/30/1996
  • Issued: 11/09/1999
  • Est. Priority Date: 09/30/1996
  • Status: Expired due to Term
First Claim
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1. A method for automatically locating a desired region of interest (ROI) in an original digital image having a plurality of pixel intensity values, comprising:

  • (a) obtaining digital image intensity data representative of an original digital image;

    (b) forming a histogram using said image intensity data, wherein one axis of said histogram indicates image intensity value and an orthogonal axis of said histogram indicates image pixel count;

    (c) determining a threshold image intensity value from said histogram as being representative of a minimum image intensity value that can possibly be from a desired ROI by;

    (c1) determining a point in said histogram representative of a noise peak in said image intensity data; and

    (c2) processing said histogram so as to find as said threshold intensity value that image intensity value wherein a portion of said processed histogram that follows said noise peak first exhibits a change to a positive curvature;

    (d) creating a mask image from said original digital image, said mask image having image pixels at grid coordinate positions corresponding to similarly positioned pixels in said original digital image, by setting all image pixels in the mask image grid to one of at least a maximum and a minimum intensity value, depending upon a comparison of the threshold intensity value to the image intensity value of the similarly positioned pixel in the original digital image; and

    (e) processing said mask image so as to define at least one contiguous area of pixels in said mask image having a common intensity value, said at least one area comprising the desired ROI.

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