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Pattern Analysis and Machine Intelligence, IEEE Transactions on

Issue 1 • Date Jan 1988

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Displaying Results 1 - 12 of 12
  • A monolithic Hough transform processor based on restructurable VLSI

    Page(s): 106 - 110
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    The implementation of a Hough transform processor using a wafer-scale-integration technology, restructurable VLSI circuit is described. The Hough transform is typically used as a grouping operation in an image processing sequence. The transform discussed here groups pixels in order to extract linear features. This calculation is realized with a wafer-scale processor that allows a complete line extraction system to be integrated on a single PC board. Also discussed is the use of the CAD tools that allowed this processor to be realized without incurring silicon layout and processing overhead View full abstract»

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  • A pipelined image analysis system using custom integrated circuits

    Page(s): 110 - 116
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    The requirements of a computer vision system in relation to industrial applications are studied. It is concluded that for the iconic image-processing part, a pipeline system built around a custom integrated circuit is preferred. This custom integrated circuit makes it possible to realize four basic operations in a compact way: shape recognition, mask generation, programmable image delay, and subsample filtering. An example that has been processed by a hardware realization of such a pipeline system is provided View full abstract»

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  • A line extraction method for automated SEM inspection of VLSI resist

    Page(s): 117 - 120
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    A precision digital edge-line-detection method is presented that was developed for extracting edge contours of resist lines of submicrometer width as imaged by scanning electron microscopy, as a means of inspection in integrated circuit fabrication. The method is based on a modification of the Hough transform View full abstract»

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  • Structured highlight inspection of specular surfaces

    Page(s): 44 - 55
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    An approach to illumination and imaging of specular surfaces that yields three-dimensional shape information is described. The structured highlight approach uses a scanned array of point sources and images of the resulting reflected highlights to compute local surface height and orientation. A prototype structured highlight inspection system, called SHINY, has been implemented. SHINY demonstrates the determination of surface shape for several test objects including solder joints. The current SHINY system makes the distant-source assumption and requires only one camera. A stereo structured highlight system using two cameras is proposed to determine surface-element orientation for objects in a much larger field of view. Analysis and description of the algorithms are included. The proposed structured highlight techniques are promising for many industrial tasks View full abstract»

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  • Measuring photolithographic overlay accuracy and critical dimensions by correlating binarized Laplacian of Gaussian convolutions

    Page(s): 17 - 30
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    A technique is described for measuring overlay accuracy and critical dimensions in IC manufacture and similar fields, based on a theory originally developed for matching binocular stereo images. The method uses targets composed of small elements that can be at the minimum feature size of the photolithographic process. Alignment is measured using clusters of those elements rather than the small elements individually. This makes the method insensitive to many of the imaging effects that have plagued other approaches, such as interference fringes and edge topology differences between process steps. The method is tolerant of high noise levels, which allows operation on process layers that produce low-contrast images or high-noise backgrounds as is the case when aligning resist over metal. Adding an appropriate bar grating to the alignment target causes element size changes to induce a proportional shift in alignment, allowing critical dimensions to be measured by the alignment technique View full abstract»

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  • A system for PCB automated inspection using fluorescent light

    Page(s): 69 - 78
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    Research was performed on the detection of faults such as shorts, cuts, and nicks in a printed circuit board pattern. The possibility was investigated of detecting a pattern by illuminating a printed circuit board with violet or ultraviolet rays and detecting the pattern using the (yellow or other) fluorescent light emitted by the base material consisting of glass-epoxy or glass-polyimide, etc. It was found that the pattern could be detected clearly by selecting an optical fiber that would separate the emitted fluorescent light from the illumination and using a detector consisting of a high-sensitivity TV camera that produces a silhouette image in which the base material is bright and the pattern is dark. A printed-circuit-board pattern inspector using this approach was developed. Test operation of the inspector in a plant demonstrated that it performs consistently good pattern inspections View full abstract»

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  • Automatic solder joint inspection

    Page(s): 31 - 43
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    The task of automating the visual inspection of pin-in-hole solder joints is addressed. Two approaches are explored: statistical pattern recognition and expert systems. An objective dimensionality-reduction method is used to enhance the performance of traditional statistical pattern recognition approaches by decorrelating feature data, generating feature weights, and reducing run-time computations. The expert system uses features in a manner more analogous to the visual clues that a human inspector would rely on for classification. Rules using these cues are developed, and a voting scheme is implemented to accumulate classification evidence incrementally. Both methods compared favorably with human inspector performance View full abstract»

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  • An automatic wafer inspection system using pipelined image processing techniques

    Page(s): 4 - 16
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    An automatic wafer pattern inspection system has been developed that can detect defective patterns 6 μm or larger in multilayered wafer patterns at a speed 30 times faster than that of a human inspector. The false-alarm rate is less than 0.5 occurrences/chip. This performance is achieved mainly by the use of a special comparison method between two adjacent patterns obtained through a single optical setup, and also by the use of digital design pattern data (CAD data). The main functions of the design pattern data are to specify the inspection area, to designate optimum parameters for inspection, and to separate defective portions into different layers, thereby facilitating the classification of the defects. All image processing is performed in one pass by a high-speed pipeline-structured image processor that can analyze an input image signal at a 7 MHz video rate View full abstract»

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  • A rule based approach for visual pattern inspection

    Page(s): 56 - 68
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    The authors investigate the use of a priori knowledge about a scene to coordinate and control bilevel image segmentation, interpretation, and shape inspection of different objects in the scene. The approach is composed of two main steps. The first step consists of proper segmentation and labeling of individual regions in the image for subsequent ease in interpretation. General as well as scene-specific knowledge is used to improve the segmentation and interpretation processes. Once every region in the image has been identified, the second step proceeds by testing different regions to ensure they meet the design requirements, which are formalized by a set of rules. Morphological techniques are used to extract certain features from the previously processed image for rule verification purposes. As a specific example, results for detecting defects in printed circuit boards are presented View full abstract»

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  • Texture measures for carpet wear assessment

    Page(s): 92 - 105
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    Two standard approaches for texture analysis make use of numerical features of the second-order gray-level statistics, and on first-order statistics of gray-level differences, respectively. Feature sets of these types, all designed analogously, were used to analyze four sets of carpet samples exposed to different degrees of wear. It was found that some of the features extracted from the spatial gray-level-dependence matrix, neighboring gray-level-dependence matrix, gray-level difference method, and the gray-level run-length method allowed discrimination of degrees of wear in wool carpet. The methods developed could be of use in quality control View full abstract»

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  • Automated X-ray inspection of aluminum castings

    Page(s): 79 - 91
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    The experience gained with several approaches to automatic flaw detection in X-ray images of cast aluminum wheels is described. Basic problems are mentioned, and the applicability of segmentation methods to actual inspection tasks is demonstrated. The discussion focuses on the definition, extraction, and combination of local features for pixel classification. Results of pilot tests are described briefly. Further investigations are suggested, aiming at more generality of the methods and greater stability of the segmentation View full abstract»

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  • A real-time processor for the Hough transform

    Page(s): 121 - 125
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    The Hough transform method for recognition can cope effectively with noisy backgrounds and gaps in boundaries. However, long computation time and large memory requirements have prevented it from being used in real-time applications. An architecture devised to solve those problems, with a focus on detecting straight lines, is presented. Examples are given of the use of an experimental hardware model for automatic inspection and measurement of objects in factories and laboratories. It took less than one second from picture input to straight line parameter reproduction for these examples View full abstract»

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Aims & Scope

The IEEE Transactions on Pattern Analysis and Machine Intelligence (TPAMI) is published monthly. Its editorial board strives to present most important research results in areas within TPAMI's scope.

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Editor-in-Chief
David A. Forsyth
University of Illinois