Patent ID: 8737725

Claim:
A method for training a learning-based classifier comprising: generating a plurality of positive training samples and a plurality of negative training samples based on annotated training images; extracting a plurality of features for each of the positive training samples and the negative training samples, the plurality of features comprising an extended Haar feature set including at least one tip feature; and training a discriminative classifier based on the features extracted for the positive training samples and the negative training samples, wherein the step of extracting a plurality of features for each of the positive training samples and the negative training samples comprises: for each positive training sample and negative training sample, extracting the at least one tip feature by: calculating a sum of pixel intensities in a first rectangle positioned adjacent to the training sample in a first direction; and subtracting a sum of pixel intensities in a second rectangle positioned adjacent to the training sample in a second direction that is opposite the first direction and third and fourth rectangles that positioned on opposite sides of the first rectangle and adjacent to the second rectangle in the first direction from the sum of pixel intensities in the first rectangle.