Patent ID: 8416986

Claim:
A method executable by a digital processing logic to automatically identify a target in an image having a plurality of pixels, each pixel being associated with a pixel value, the method comprising: selecting a subset of the plurality of pixels in the image; determining first slope estimates representative of various samples of a slope measurement in a first direction of the image, each first slope estimate based upon a difference in the pixel values of at least some of the pixels in the subset scaled using a value that is based upon the distance between the pixels in the image representing an average slope per pixel; determining, using a first rank order filter implemented with the digital processing logic, a first slope from the first slope estimates; determining second slope estimates representative of various samples of a slope measurement in a second direction of the image, each second slope estimate based upon a difference in the pixel values of at least some of the pixels in the subset scaled using a value that is based upon the distance between the pixels in the image representing an average slop per pixel; determining, using a second rank order filter implemented with the digital processing logic, a second slope from the second slope estimates; compensating the values of at least some of the plurality of pixels in the digital processing logic for the effects of a sloping background using the first and the second slopes, thereby creating a plurality of compensated values; processing the compensated values by the digital processing logic to determine if the target is present in at least one of the plurality of pixels; and providing an output from the digital processing logic that indicates if the target is present.