Determining an orientation direction of a color edge at a pixel location in a color image

摘要

What is disclosed is a system and method for determining an orientation direction of a color edge at a given pixel location in a binary color image. The orientation direction of the color edge is determined from eight pixel counts with each pixel count being a total number of pixels in each of eight regions of a window centered about a candidate pixel which resides along the color edge. The eight regions are associated with 8 compass points. The orientation of the edge is determined by a 1st, 2nd and 3rd tier control bits which are based upon the pixel counts of each region. The 1st, 2nd and 3rd tier control bits collectively form a 3-bit word. The 3-bit word defines the orientation direction. The teachings hereof provide an efficient way of performing binary edge orientation detection by making uses of intermediate results to simultaneously encode the edge orientation.

主权项

1. A circuit for determining an orientation direction of a color edge at a pixel location in a color image, said system comprising:
a first tier of circuitry receiving, as input, eight pixel counts each comprising a total number of pixels of a color in a region of a window centered on a selected pixel in a bitmap of a halftoned color image, said first tier circuit generating, as output, four largest pixel counts of said eight input pixel counts and four 1st tier control bits used to select said four largest pixel counts; a second tier of circuitry receiving, as input, said four 1st tier control bits and said four largest pixel counts, said second tier circuit generating, as output, two 2nd tier control bits used to select two of the lowest pixel counts of said four largest pixel counts, and to select two of said four 1st tier control bits; and a third tier of circuitry receiving, as input, said two selected lowest pixel counts, two of said selected 1st tier control bits, and two of said selected 2nd tier control bits, said third tier of circuitry generating, as output, a 3rd tier control bit used to select one of said two selected 1st tier control bits, one of said two 2nd tier control bits, and a minimum pixel count of said two lowest pixel counts, said selected 1st, 2nd and 3rd tier control bits comprising a 3-bit word which defines an orientation direction of said color edge.