Patent ID: 6917721

Claim:
A method of processing an image, the method comprising: determining a first discrete filter sequence, F 1 ; determining a second discrete filter sequence, F 2 ; determining a third discrete filter sequence, F 3 ; filtering the image using the first discrete filter sequence to generate a correlation sequence including a first correlation value, Y 1 [n 0 ]; locating a zero crossing pixel location, n 0 , within the image using the correlation sequence; filtering the image at pixel location n 0 using the second discrete filter sequence to generate a second correlation value, Y 2 [n 0 ]; filtering the image at pixel location n 0 using the third discrete filter sequence to generate a third correlation value, Y 3 [n 0 ]; determining a sub-pixel position offset, a, at the zero crossing pixel location using the first correlation value, Y 1 [n 0 ], the second correlation value Y 2 [n 0 ], and the third correlation value, Y 3 [n 0 ]; and determining an edge location, t 0 , of the image using the pixel location, n 0 , and the sub-pixel position offset, a.