Patent ID: 6269194
Filing Date: 2001-07-31
Classification: G06K,G06T

Abstract:
A machine vision apparatus implementing thresholding in a vision system application involving comparison of a first image and a second image comprising:an image acquisition device capturing said first image comprising a plurality of first image pixels and said second image comprising a plurality of second image pixels:a memory receiving from said image acquisition device first image information defining said plurality of first image pixels as a respective gray level value for each of said plurality of first image pixels, and receiving second image information defining said plurality of second image pixels as a respective gray level value for each of said plurality of second image pixels; anda processor generating a dynamic threshold image as a function of said gray level value of said first image pixels and said gray level values of said second image pixels, said processor subtracting gray level values of said second image pixels from gray level values of said first image pixels to provide a subtracted image having a plurality of subtracted image pixel values, and said processor implementing thresholding by subtracting said subtracted image from said dynamic threshold image, wherein in generating said dynamic threshold image, said processor generates a positive dynamic threshold image and a negative dynamic threshold image as a function of said gray level values of said first image pixels and said gray level values of said second image pixels using a positive threshold map and a negative threshold map, respectively, which are pixel maps that mask out areas that are not relevant, and implements adaptive gain in a form of pixel thresholds that are proportional to a difference in gray level value between a feature of interest in a foreground and a local background.