1. A method for determining the presence of an object of interest in a target image, the method comprising: mapping a template image discrete curve to a mapped template image discrete curve using a mapping operator; acquiring the target image; determining a target image discrete curve from the target image, wherein the target image discrete curve corresponds to a respective object in the target image; performing shape matching on the mapped target image discrete curve and a mapped template image discrete curve, wherein the mapped template image discrete curve corresponds to the object of interest, wherein said performing shape matching computes a distance for the mapped target image discrete curve relative to the mapped template image discrete curve; and generating pattern matching results based on the distances.