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Proceedings Paper

Implementation Of Real-Time Perspective Correction
Author(s): Frederick M. Waltz
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Paper Abstract

In some applications of machine vision, space limitations force the placement of the camera at an angle other than normal to the surface being inspected, resulting in perspective distortion of the image. This makes precision measurement difficult or impossible, since a given number of pixels corresponds to different distances in different parts of the image. In other applications, the object has more than one facet, so that it is impossible to get orthogonal views of all facets with a single camera. Perspective correction algorithms involve massive amounts of calculation, making them either prohibitively slow or prohibitively expensive for most inspection applications. This paper describes a method for carrying out precision perspective correction for 485 by 512 grey-level images at 30 frames per second (or 242 by 512 images at 60 fields per second) using moderately-priced commercially-available board-level hardware to do sub-pixel interpolation. In addition, a scheme for carrying out arbitrary predefined sub-pixel warping on a pixel-by-pixel basis in real time is described, using the same hardware and a relatively simple adapter/connector. Thus, lens distortion (e.g., pincushion and barrel distortion) and camera nonuniformity (e.g., nonlinear raster scan) can be "calibrated out" in real time at moderate cost.

Paper Details

Date Published: 22 March 1988
PDF: 5 pages
Proc. SPIE 0849, Automated Inspection and High-Speed Vision Architectures, (22 March 1988); doi: 10.1117/12.942840
Show Author Affiliations
Frederick M. Waltz, 3M Company (United States)

Published in SPIE Proceedings Vol. 0849:
Automated Inspection and High-Speed Vision Architectures
Rolf-Juergen Ahlers; Michael J. W. Chen, Editor(s)

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