Determination of Background Gray-level for Accurate Measurement of Particles in using Image Processing Method

Title & Authors
Determination of Background Gray-level for Accurate Measurement of Particles in using Image Processing Method
Koh, Kwang-Uoong; Lee, Sang-Yong;

Abstract
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 $\small{pm}$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 $\small{pm}$5%. The depth-of-field for the VC-applicable particle-size range is largely dependent on the background gray-level. On the other hand, the depth-of-field for the GI-applicable particle-size range changes only slightly with the background gray-level. To keep the normalized standard deviation of the particle size within 0.1, the background gray-level should be set 160$\small{pm}$20 for both the VC-applicable and GI-applicable ranges which cover the particle size between $\small{10{\mu}m}$ and $\small{300{\mu}m}$.
Keywords
Image Processing;In-focus Criterion;Particle Size Measurement;Gradient Indicator(Gl);Normalized Value of Contrast(VC);Depth-of-field;Background Gray-level;
Language
Korean
Cited by
References
1.
Chigier, N., 1983, 'Drop Size and Velocity Instrumentation,' Prog. Energy Combust. Sci., Vol. 9, pp. 155 -177

2.
이상용, 1996, 액체의 미립화, 민음사

3.
Ahlers, K. D. and Alexander, D. R., 1985, 'Microcomputer Based Digital Image Processing System Developed to Count and Size Laser-Generated Small Particle Images,' Opt. Eng., Vol. 24, No.6, pp, 1060-1065

4.
Kim, I. G. and Lee, S. Y., 1990, 'A Simple Technique for Sizing and Counting of Spray Drops Using Digital Image Processing,' Exp. Thermal Fluid Sci., Vol. 3, pp. 214-221

5.
Ow, C. S. and Crane, R. I., 1981, 'Pattern Recognition Procedures for a Television-Minicomputer Spray Droplet Sizing System,' J. lnst. Energy, Vol. 54, No. 430, pp. 119 -123

6.
Weiss, B. A., Derov, P., DeBiase, D. and Simmons, H. C., 1984, 'Fluid Particle Sizing Using a Fully Automated Optical Imaging System, Opt. Eng., Vol. 23, No.5, pp. 561-566

7.
김주연, 추정호, 이상용, 1998, '입경 측정을 위한 영상처리기법의 개선,' 대한기계학회 논문집, Vol. 22, No. 5, pp, 561-566

8.
Lee, S. Y., Park, B. S. and Kim, I. G., 1991, 'Gray Level Factors Used in Image Processing of Two-Dimensional Drop Images,' Atomization and Sprays, Vol. 1, No.4, pp. 389-400

9.
Kim, K. S. and Kim, S. S., 1994, 'Drop Sizing and Depth-of-field Correction in TV Imaging,' Atomization and Sprays, Vol. 4, No. 1, pp. 65-78

10.
Talley, D. G. and Hassoni, M., 1992, 'Accounting for Depth of Field in Sizing Spherical Particles by Imaging,' Atomization and Sprays, Vol. 2, No. 1, pp. 385 -409

11.
Mohammadi, A., Miwa, K., Ishiyama, K. and Abe, M., 1998, 'Measurement of Droplet Size, Shape and Velocity in Diesel Sprays using a Single and Double Nano-spark Photography Method,' JSME International Journal, series B, Vol. 41, No. 1, pp. 7-12

12.
고광웅, 김주연, 이상용, 1999, '입경측정을 위한 영상처리기법에서 입자 초점면 존재 판단기준의 설정,' 대한기계학회 논문집, Vol. 23, No.3, pp. 398 -407