Apparatus and methods for coding and storing raster scan images
First Claim
1. Apparatus for use in coding and storing raster scan images, comprisingmeans for scanning images in a series of raster scan lines,detecting means for detecting discontinuities as they occur in a raster scan line and for deriving both respective position signals representative of the positions in the line of the discontinuities and respective segment signals representing directions of segments of boundaries formed by discontinuities in the line, each segment direction including a positive or negative polarity determined by the direction of a boundary of which that segment forms part, the positive direction being a predetermined direction of traverse around a shape which is enclosed by the boundary,a first store coupled to the detection means for storing chains of the segment signals in which the chains represent respective discontinuities in an image being scanned, the contents of the first store forming, when a scan is complete, part of a coded and stored version of an image scanned,logic means for determining when a new discontinuity not connected to previously-detected discontinuities is detected,means coupled to the logic means for allocating identifying signals for the said chains when a said new discontinuity is detected, anda second store with address input coupled to the said detection means and a content input coupled to the said means for allocating identifying signals, the second store having first and second arrays of storage locations, one location in each said array for each pixel in a scan line, the first and second arrays being used, in operation, to store for each line and for an interval of one line period, the identifying signals of chains having a segment starting and finishing, respectively, as determined by the positive direction, at locations corresponding to the line positions of the starting and finishing segments,the logic means being coupled to read the second store as each point in said raster scan line is scanned at the location relating to the corresponding point in the previous said raster scan line, and the logic means causing the first store to store segment signals representing each new segment either as an end of a new chain if no chain identifying signal is stored at the location read, or as a further segment signal in an existing chain if the identifying signal of the existing chain is found at the location read.
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Abstract
In automatically checking circuit boards by raster scanning, it is useful to code and store conductor boundaries for later analysis. Coding time can be reduced by storing an identification of a chain of boundary segments in one of two arrays each time a boundary is detected in a scan line, the identification being stored at an address corresponding to the position of the segment detected. At the same time signals describing the segment are stored in another store at an address related to the identification. When in the next scan line a boundary segment is detected, an address corresponding to its position is used to address the said array and if an identification is found, the new segment is stored in the other store as part of the chain identified. In order to reduce the size of the other store signals describing segments are not stored in areas allocated to chains but in the next vacant location and a RAM stores links between segments.
85 Citations
4 Claims
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1. Apparatus for use in coding and storing raster scan images, comprising
means for scanning images in a series of raster scan lines, detecting means for detecting discontinuities as they occur in a raster scan line and for deriving both respective position signals representative of the positions in the line of the discontinuities and respective segment signals representing directions of segments of boundaries formed by discontinuities in the line, each segment direction including a positive or negative polarity determined by the direction of a boundary of which that segment forms part, the positive direction being a predetermined direction of traverse around a shape which is enclosed by the boundary, a first store coupled to the detection means for storing chains of the segment signals in which the chains represent respective discontinuities in an image being scanned, the contents of the first store forming, when a scan is complete, part of a coded and stored version of an image scanned, logic means for determining when a new discontinuity not connected to previously-detected discontinuities is detected, means coupled to the logic means for allocating identifying signals for the said chains when a said new discontinuity is detected, and a second store with address input coupled to the said detection means and a content input coupled to the said means for allocating identifying signals, the second store having first and second arrays of storage locations, one location in each said array for each pixel in a scan line, the first and second arrays being used, in operation, to store for each line and for an interval of one line period, the identifying signals of chains having a segment starting and finishing, respectively, as determined by the positive direction, at locations corresponding to the line positions of the starting and finishing segments, the logic means being coupled to read the second store as each point in said raster scan line is scanned at the location relating to the corresponding point in the previous said raster scan line, and the logic means causing the first store to store segment signals representing each new segment either as an end of a new chain if no chain identifying signal is stored at the location read, or as a further segment signal in an existing chain if the identifying signal of the existing chain is found at the location read.
Specification
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- Resources
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Current AssigneeNational Research Development Corporation
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Original AssigneeNational Research Development Corporation
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InventorsWest, Geoffrey A. W., Hill, Walter J.
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Primary Examiner(s)Boudreau, Leo H.
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Assistant Examiner(s)Mancuso, Joseph
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Application NumberUS06/601,340Time in Patent Office973 DaysField of Search382/26, 382/56, 382/21, 382/22, 382/20, 382/8, 364/900 MS File, 364/200 MS File, 358/106, 358/107US Class Current382/197CPC Class CodesG01B 11/024 by means of diode-array sca...G06T 2207/30141 Printed circuit board [PCB]G06T 7/12 Edge-based segmentationG06T 9/20 Contour coding, e.g. using ...G06V 10/469 Contour-based spatial repre...
