Patent ID: 6912309

Claim:
A method for identifying objects in an image comprising: processing the image with a gradient operator to produce a gradient magnitude and direction for each pixel; determining a number of different gradient directions in a portion of the processed image; identifying the portion of the processed image as an object if the number of different gradient directions exceeds a threshold number of gradient directions; and encoding the gradient direction for each pixel into a binary value, wherein the determining step comprises performing a binary OR operation using the encoded gradient directions in a vertical direction of the portion of the processed image to produce a horizontal array of encoded gradient directions; performing a binary OR operation using the horizontal array of encoded gradient directions to produce a binary value; and comparing the binary value to a predetermined set of binary values, each binary value in the predetermined set of binary values corresponding to a number of edge directions, wherein the number of different gradient directions in the portion of the processed image is determined using said comparison.