Patent ID: 8300949

Claim:
A method for determining edge features of an image comprising: (a) filtering at least a portion of said image to attenuate high frequency signals of said image to an extent greater than low frequency signals of said image; (b) performing a one-dimensional search in a first horizontal direction relative to a particular pixel of said image to determine a first horizontal direction local maximum; (c) performing a one-dimensional search in a second horizontal direction relative to said particular pixel of said image to determine a second horizontal direction local maximum; (d) calculating a horizontal gradient based upon said first horizontal direction local maximum and said second horizontal direction local maximum; (e) performing a one-dimensional search in a first vertical direction relative to a particular pixel of said image to determine a first vertical direction local maximum; (f) performing a one-dimensional search in a second vertical direction relative to said particular pixel of said image to determine a second vertical direction local maximum; (g) calculating a vertical gradient based upon said first vertical direction local maximum and said second vertical direction local maximum; (h) calculating a gradient for said particular pixel based upon said horizontal gradient and said vertical gradient.