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Subpixel Measurements Using a Moment-Based Edge Operator
December 1989 (vol. 11 no. 12)
pp. 1293-1309

Recent results in precision measurements using computer vision are presented. An edge operator based on two-dimensional spatial moments is given. The operator can be implemented for virtually any size of window and has been shown to locate edges in digitized images to a twentieth of a pixel. This accuracy is unaffected by additive or multiplicative changes to the data values. The precision is achieved by correcting for many of the deterministic errors caused by nonideal edge profiles using a lookup table to correct the original estimates of edge orientation and location. This table is generated using a synthesized edge which is located at various subpixel locations and various orientations. The operator is extended to accommodate nonideal edge profiles and rectangularly sampled pixels. The technique is applied to the measurement of imaged machined metal parts. Theoretical and experimental noise analyses show that the operator has relatively small bias in the presence of noise.

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Index Terms:
subpixel measurements; pattern recognition; picture processing; edge location; moment-based edge operator; computer vision; two-dimensional spatial moments; digitized images; deterministic errors; lookup table; edge orientation; imaged machined metal parts; noise analyses; computerised pattern recognition; computerised picture processing; table lookup
E.P. Lyvers, O.R. Mitchell, M.L. Akey, A.P. Reeves, "Subpixel Measurements Using a Moment-Based Edge Operator," IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 11, no. 12, pp. 1293-1309, Dec. 1989, doi:10.1109/34.41367
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