Subpixel edge detection and estimation with amicroprocessor-controlled line scan camera
Li, Y.-S.; Young, T.Y.; Magerl, J.A.
Industrial Electronics, IEEE Transactions on
Volume 35, Issue 1, Feb 1988 Page(s):105 - 112
Digital Object Identifier 10.1109/41.3072
Summary:A microprocessor-controlled line scan camera system for measuring
edges and lengths of steel strips is described, and the problem of
subpixel edge detection and estimation in a line image is considered.
The edge image is assumed to change gradually in its intensity, and the
true edge location may be between pixels. Detection and estimation of
edges are based on measurement of gray values of the line images at a
limited number of pixels. A two-stage approach is presented. At the
first stage, a computationally simple discrete-template-matching method
is used to place the estimated edge point to the nearest pixel value.
Three second-stage methods designed for subpixel estimation are
examined. The modified Chebyshev polynomial and the three-point
interpolation method do not require much knowledge on the shape of the
edge intensity. If the functional form of the edge is known, a
least-square estimation method may be used for better accuracy. In the
case of nonstationary Poisson noise, a recursive maximum-likelihood
method for the first-stage edge detection, followed by subpixel
estimation, is proposed
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