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Determination of Background Gray-level for Accurate Measurement of Particles in using Image Processing Method
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 Title & Authors
Determination of Background Gray-level for Accurate Measurement of Particles in using Image Processing Method
Koh, Kwang-Uoong; Lee, Sang-Yong;
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In this study, experiments have been performed to examine the effects of background gray-level on the depth-of-field and on the in-focus criteria. The normalized value of contrast(VC) and the gradient indicator(GI) were used as the in-focus criteria for the small and the large size-ranges of particles, respectively. The slightly larger number of pixels were detected with the brighter background. The maximum of the normalized value of contrast(VCmax) is decreased with the brighter background and its deviation from that with the background gray-level of 160 turned out to be about 15% when the background gray-level changes from 100 to 200. However, the maximum gradient indicator(GImax) changes with the background gray-level within only 5%. The depth-of-field for the VC-applicable particle-size range is largely dependent on the background gray-level. On the other hand, the depth-of-field for the GI-applicable particle-size range changes only slightly with the background gray-level. To keep the normalized standard deviation of the particle size within 0.1, the background gray-level should be set 16020 for both the VC-applicable and GI-applicable ranges which cover the particle size between and .
Image Processing;In-focus Criterion;Particle Size Measurement;Gradient Indicator(Gl);Normalized Value of Contrast(VC);Depth-of-field;Background Gray-level;
 Cited by
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