Patent Document ID: 5583659
Application ID: 08338051
Patent Status: 1

Claim One:
1. Apparatus for thresholding an input gray-scale image into a first output image, wherein said input image is formed of input pixels each having a multi-bit gray-scale pixel value associated therewith, and wherein said first output image is formed of pixels each having a corresponding output pixel value associated therewith, said apparatus comprising: means, responsive to a plurality of pixel values in the input image, for ascertaining an area gradient value for a first window, of pre-defined size, of intensity gradient values associated with ones of the pixel values centered about a current pixel position, (i,j) (where i and j are pixel indices), in the input image; means, responsive to a second window, of pre-defined size, of input pixels centered about the current pixel position (i,j) in the input image, for determining a maximum pixel value and a minimum pixel value of the pixel values contained within said second window; and means, responsive to the area gradient value and the maximum and minimum pixel values, for thresholding a current one of the pixel values for the current pixel position (i,j) in the input image into an output pixel value at a corresponding position in the first output image.