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Shape from Focus
August 1994 (vol. 16 no. 8)
pp. 824-831

The shape from focus method presented here uses different focus levels to obtain a sequence of object images. The sum-modified-Laplacian (SML) operator is developed to provide local measures of the quality of image focus. The operator is applied to the image sequence to determine a set of focus measures at each image point. A depth estimation algorithm interpolates a small number of focus measure values to obtain accurate depth estimates. A fully automated shape from focus system has been implemented using an optical microscope and tested on a variety of industrial samples. Experimental results are presented that demonstrate the accuracy and robustness of the proposed method. These results suggest shape from focus to be an effective approach for a variety of challenging visual inspection tasks.

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Index Terms:
image sequences; image texture; shape from focus method; sum-modified-Laplacian operator; image focus quality; depth estimation algorithm; optical microscope; accuracy; robustness; visual inspection tasks
S.K. Nayar, Y. Nakagawa, "Shape from Focus," IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 16, no. 8, pp. 824-831, Aug. 1994, doi:10.1109/34.308479
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