Abstract: 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.

Abstract: An efficient and reliable method and apparatus is disclosed that finds a reference point of an object profile within an image when the object is of an unknown size. The object profile is modeled using a synthetic labeled-projection model, which in conjunction with the image, is projected over a portion of the image of the object profile to derive a histogram. The histogram is normalized and a maximum of a first derivative of the histogram is defined for that position. The position of the labeled-projection model is moved relative to the image, and the process is repeated until a selected portion of the image has been examined. The first derivative of the normalized labeled projection is greatest when a feature of the image and the feature denoted by a specific synthetic label of the labeled-projection model are aligned. The method and apparatus can locate the center of the object with reliability, because use of the labeled-projection model and the histogram minimizes the * effects of image artifacts.

Abstract: A method and apparatus is provided that detects extended defects in a surface, by detecting connected features and classifying the connected features so as to identify defects. A method and apparatus is described which processes an image for edges, thresholds the edge and then determines whether the edges are connected features by examining the orientation of the edges compared to their neighboring edges. Application of the method to read/write heads in a storage-drive assembly application is disclosed. Particular enhancements of the method and apparatus for that application are described, including classifying the defects on a head based on their relationship to the boundary of the head, and applying hysteresis thresholding or diffusion to identify cracks which interfere with the function of the heads.

Abstract: An image of an actual pattern of discrete objects is analyzed with respect to a model representing a predefined ideal pattern of objects. Initial processing is performed on only a portion of the image associated with ones of the objects located in an original neighborhood within the image to determine information about an affine transformation of the actual pattern of the discrete objects relative to the predefined ideal pattern. Additional processing is performed on other portions of the image based on the results of the initial processing. Initial processing is performed with respect to a first part of the image by operating on only a first portion of all of the digital data that represents that first part of the image.