Atomization and Sprays Journal of the International Institutes for Liquid Atomization and Spray Systems

ISSN for PRINT: 1045-5110

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2001, Volume11

Issue 4

186 pages

Issue price - $75.00

Kwang Uoong Koh
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Taejon, Korea

Joo Youn Kim
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1, Kusong-Dong, Yusong-Gu, Taejon, 305-701 Korea

Sang Yong Lee
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1, Kusong-Dong, Yusong-Gu, Taejon, 305-701 Korea

In the present study, in-focus criteria and depth of field in image processing of spray particles within the size range 10–300 mm have been examined. As the indices of the in-focus criteria, the critical normalized value of contrast (VC_critical) proposed earlier was carefully reviewed, and the concept of the critical gradient indicator (GI_critical) was newly introduced. The criterion with VC_critical) was confirmed to be appropriate only for the small particle range (Ј 30 mm). In contrast, the criterion with GI_critical was determined to be appropriate for large particles і 30 mm). The dependence of the depth of field on the values of VC_critical and GI_critical was examined. The depth of field decreases with higher values of VC_critical and GI_critical , and varies linearly with particle size in both VC- and GI-applicable ranges. To keep the normalized standard deviation of the measurements below 0.1 while maintaining the continuity of the depth-of-field variation at the borderline of 30 mm, the adjustable constants C and DGI for VC_critical and GI_critical should be set to 0.85 and 0.22, respectively, for the present optical setup.

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