Methods and apparatuses for detecting similar features within an image

The invention provides methods and apparatuses for finding features that are similar in the image. The invention finds the similar features by searching portions of the image for features that are substantially similar to a feature prototype. First, individual features in the image are located and designated candidate features, and optionally a spatial pattern representing a majority of the candidate features is generated. Next, feature profiles are generated therefrom, and the feature prototype is constructed using at least a subset of feature profiles. An example is described wherein the object is a ball grid array, the similar features are the solder balls on the ball grid array, the feature profiles are local images of balls of a ball grid array, and the feature prototype is an average of a sub-set of the local images of the balls.