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Proceedings Paper

Color metric for production quality control
Author(s): Anthony J. McCollum; Andrew K. Forrest
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Paper Abstract

A real-time color quality control metric for planar surfaces has been developed. This is a differencing method that compares the color histogram of a test object with that of a standard obtained off-line. To reduce computational effort, three 1D histograms are formed by projecting the reference color histogram on to its principal axes. A metric value for each of the axes is then obtained by taking the RMS value of the differences between the corresponding entries in the histograms of the sample and reference objects. A model of the behavior of the metric has been developed and compared to the practical case where one of the color channels is attenuated. The major axis is generally observed to form the least sensitive color metric component for the purposes of quality control. It is argued that the projections on to the minor axis are theoretically expected to produce the most sensitive component because this is a null channel with respect to the reference image. In practice it is observed that this is often the case. The method has been evaluated using production samples of ceramic tiles. Results are presented showing clustering of the experimental data corresponding to tiles of different grades.

Paper Details

Date Published: 16 September 1999
PDF: 12 pages
Proc. SPIE 3826, Polarization and Color Techniques in Industrial Inspection, (16 September 1999); doi: 10.1117/12.364322
Show Author Affiliations
Anthony J. McCollum, Imperial College of Science, Technology and Medicine (United Kingdom)
Andrew K. Forrest, Imperial College of Science, Technology and Medicine (United Kingdom)


Published in SPIE Proceedings Vol. 3826:
Polarization and Color Techniques in Industrial Inspection

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