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Low Contrast 특성을 갖는 LCD 편광필름 결함의 크기 자동 검출
박덕천(Duckchun Park),주효남(Hyonam Joo),류근호(Keun-Ho Rew) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.5
In this paper, segmenting and classifying low contrast defects on flat panel display is one of the key problems for automatic inspection system in practice. Problems become more complicated when the quality of acquired image is degraded by the illumination irregularity. Many algorithms are developed and implemented successfully for the defects segmentation. However, vision algorithms are inherently prone to be dependent on parameters to be set manually. In this paper, one morphological segmentation algorithm is chosen and a technique using frequency domain analysis of input images is developed for automatically selection the morphological parameter. An extensive statistical performance analysis is performed to compare the developed algorithms.
QFN 패키지의 Resin Bleed와 Melting 검출 알고리즘
왕명걸(Mingjie Wang),박덕천(Duckchun Park),주효남(Hyonam Joo),김준식(Joon-Seek Kim) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.9
There are many different types of surface defects on semiconductor Integrated Chips (IC’s) caused by various factors during manufacturing process, such as Scratch, Flash, Resin bleed, and Melting. These defects must be detected and classified by an inspection system for productivity improvement and effective process control. Among defects, in particular, Resin bleed and Melting are the most difficult ones to classify accurately. The brightness value and the shape of Resin bleed and Melting defects are so similar that normally it is difficult to classify the Resin bleed and Melting. In this paper, we propose a segmenting method and a set of features for detecting and classifying the Resin bleed and Melting defects.
FPD용 컬러 필터의 수지 얼룩 결함 형상화에 관한 연구
권오민(Oh-Min Kwon),이정섭(Jung-Seob Lee),박덕천(Duckchun Park),주효남(Hyonam Joo),김준식(Joon-Seek Kim) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.8
Detecting defects on FPD (Flat Panel Display) color filter before the full panel is made is important to reduce the manufacturing cost. Among many types of defects, the low contrast blemish such as Suzi Mura is difficult to detect using standard CCD cameras. Even skilled inspectors in the inspection line can hardly identify such defects using bare eyes. To overcome this difficulty, point spectrometer has been used to analyze the spectrum to differentiate such defects [rom normal color fillers. However, scanning ever increasing-size color filters by a point spectrometer takes too long time to be used in real production line. We propose a system using a spectral camera which can be viewed as a line scan camera composed of an array of point spectrometers. Three types of lighting system that exhibit different illumination spectrums are devised together with a calibration method of the proposed spectral camera system. To visualize the defect areas, various processing algorithms to identify and to enhance the small differences in spectrum between defective and normal areas are developed. Experiments shows 85% successful visualization of real samples using the proposed system.
Extended Depth of Focus 알고리듬 파라메타 초기설정에 관한 연구
유경무(Kyungmoo Yoo),주효남(Hyonam Joo),김준식(Joonseek Kim),박덕천(Duckchun Park),최인호(Inho Choi) 한국방송·미디어공학회 2012 방송공학회논문지 Vol.17 No.4
Extended Depth of Focus (EDF) algorithms for extracting three-dimensional (3D) information from a set of optical image slices are studied by many researches recently. Due to the limited depth of focus of the microscope, only a small portion of the image slices are in focus. Most of the EDF algorithms try to find the in-focus area to generate a single focused image and a 3D depth image. Inherent to most image processing algorithms, the EDF algorithms need parameters to be properly initialized to perform successfully. In this paper, we select three popular transform-based EDF algorithms which are each based on pyramid, wavelet transform, and complex wavelet transform, and study the performance of the algorithms according to the initialization of its parameters. The parameters we considered consist of the number of levels used in the transform, the selection of the lowest level image, the window size used in high frequency filter, the noise reduction method, etc. Through extended simulation, we find a good relationship between the initialization of the parameters and the properties of both the texture and 3D ground truth images. Typically, we find that a proper initialization of the parameters improve the algorithm performance 3㏈ ~ 19㏈ over a default initialization in recovering the 3D information.