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Radiographic image processing method wherein small variation of density is selectively made clear

  • US 5,369,572 A
  • Filed: 03/20/1992
  • Issued: 11/29/1994
  • Est. Priority Date: 03/20/1991
  • Status: Expired due to Term
First Claim
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1. A method for processing a radiographic image, comprising:

  • generating and transmitting X-rays through a body using an X-ray generator to produce original image data;

    calculating an average (Sm) of the original image data of an averaging area around each pixel of said radiographic image;

    transforming the original image data of each pixel of said radiographic image to obtain a processed image data of each pixel in accordance with an equation,
    
    
    space="preserve" listing-type="equation">Q=S+ƒ

    (S-S.sub.m)where Q is the processed image data, S is the original image data, and ƒ

    (S-Sm) is a function of the difference between the original image data S and the average Sm, and has a characteristic in at least one of first and second ranges of the difference between the original image data S and the average Sm, the difference between the original image data S and the average Sm is positive in said first range and negative in said second range, and according to said characteristic, the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with an increasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is less than a predetermined value, and the absolute value |Q-S| of the difference between the processed image data Q and the original image data S varies in accordance with a decreasing monotonic function of the absolute value |S-Sm | of the difference between the original image data S and the average Sm when the absolute value |S-Sm | of the difference between the original image data S and the average Sm is more than the predetermined value; and

    outputting the processed image data to output device.

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