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Apparatus for processing digitized images

  • US 4,853,970 A
  • Filed: 11/24/1987
  • Issued: 08/01/1989
  • Est. Priority Date: 03/24/1984
  • Status: Expired due to Term
First Claim
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1. Apparatus for use in enhancing boundaries between light and dark regions of a video image depicting both continuously varying tones of gray or other color as well as two tone text or graphics or the like, said video image being represented by an array of pixels, each pixel of which has an intensity value associated therewith indicative of gray level or the like, a light and a dark region of said image being separated by a transition region wherein said image varies rapidly between light and dark, said apparatus comprising:

  • neighborhood-defining means receiving said array of pixels and, for pixels in regions depicting two tones as well as for pixels in regions depicting continuously varying tones, presenting a center pixel and a plurality of pixels forming a two-dimensional neighborhood of said center pixel;

    edge operator means receiving said center pixel and said neighborhood and determining therefrom whether said center pixel lies in a transition region, said edge operator means providing an edge bit value indicative of the disposition of said center pixel with respect to said transition region;

    point operator means for providing a binary representation of transition regions, said point operator means receiving said center pixel and said neighborhood and assigning a point bit value to said center pixel indicating whether said center pixel is dark or light based on the intensity values of said neighborhood;

    level operator means for providing a binary representation of regions of continuously varying tones, said level operator means receiving said center pixel and assigning a level bit value thereto indicating whether said center pixel is dark or light based on the continuously varying tone level being represented; and

    logic means receiving said edge bit value, said point bit value, and said level bit value, said logic means passing said point bit value to an output thereof when said edge bit value indicates said center pixel lies in a transition region and passing said level bit value to said output otherwise.

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