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Method for automatic detection of region of interest for digital x-ray detectors using a filtered histogram

  • US 6,118,892 A
  • Filed: 11/19/1998
  • Issued: 09/12/2000
  • Est. Priority Date: 11/19/1998
  • Status: Expired due to Term
First Claim
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1. A method for automatically forming a filtered subset of digital values from a first set of digital values corresponding to a plurality of picture elements representing a radiographic exposure of a subject for use in displaying a radiograph of said subject, the method comprising:

  • (1) generating a first histogram representing a frequency of occurrence of digital values within the first set of digital values;

    (2) generating an integral curve representing an integral of said first histogram;

    (3) obtaining a digital value Vpeak1, corresponding to an inflection point on the first histogram integral curve where the integral curve first changes slope starting from a point of highest digital value and traversing along the integral curve in the direction of decreasing digital values;

    (4) calculating a parameter Vtest =Vpeak1 -AR wherein AR is a parameter that represents an anatomical range of said subject;

    (5) spatially dividing the first set of digital values into multiple block subsets of digital values, each block subset comprising digital values from a neighborhood of pixels consisting of a predetermined number of picture elements;

    (6) constructing a block subset histogram representing a frequency of occurrence of digital values within each block subset;

    (7) determining on each block subset a digital value BVlow, corresponding to a predetermined low point of the block subset histogram;

    (8) comparing each BVlow to Vtest ; and

    (9) forming said filtered subset of digital values from the digital values of all the block subsets having BVlow greater than Vtest.

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