Patent ID: 7058221

Claim:
A method of recognizing an object based on pattern matching using a gray-scale normalized correlation method, comprising: storing a reference image including a foreground and a background, the foreground and the background providing a predetermined contrast pattern; inputting an image of the object, the image including a foreground and a background, the foreground and the background providing a predetermined contrast pattern; obtaining a function for giving the predetermined contrast pattern of the reference image corresponding to the predetermined contrast pattern of the input image, the function providing a predetermined form pattern, the predetermined form pattern including a rectangular pattern; and calculating a normalized correlation coefficient between the reference image and the input image using the function, the calculating step comprising: calculating an autocorrelation coefficient of the reference image by assigning a density distribution value of a background area of the reference image to a first constant value and by assigning a density distribution value of a foreground area of the reference image to a second constant value different from the first constant value; calculating a cross correlation coefficient between the reference image and the input image for the foreground and the background areas; and obtaining the normalized correlation coefficient by dividing the cross correlation coefficient by a product of the autocorrelation coefficients of the input image and the reference image.