• 한국정밀공학회지
• /
• 제16권5호통권98호
• /
• pp.48-57
• /
• 1999

Applications of thresholding technique are based on the assumption that object and background pixels in a digital image can be distinguished by their gray level values. For the segmentation of more complex images, it is necessary to resort to multiple threshold selection techniques. This paper describes a new method for multiple threshold selection of gray level images which are not clearly distinguishable from the background. The proposed method consists of three main stages. In the first stage, a probability distribution function for a gray level histogram of an image is derived. Cluster points are defined according to the probability distribution function. In the second stage, fuzzy partition matrix of the probability distribution function is generated through the fuzzy clustering process. Finally, elements of the fuzzy partition matrix are classified as clusters according to gray level values by using max-membership method. Boundary values of classified clusters are selected as multiple threshold. In order to verify the performance of the developed algorithm, automatic inspection process of ball grid array is presented.

• 한국통신학회논문지
• /
• 제29권8C호
• /
• pp.1062-1068
• /
• 2004

본 논문에서는 정확한 코너점 검출을 위하여 새로운 그레이 레벨 코너점 검출 방법을 제안한다. 새로운 코너 검출자는 코너 영역을 윈도우 크기에 따라서 동심원으로 계층을 나누어 각각의 계층에서의 코너의 각도를 구하여 코너점을 검출하도록 하였다. 또한 계층적 구조를 가지고 처리함으로써 기존의 그레이레벨 코너 검출자보다 더 빠른 처리 속도를 얻을 수 있도록 하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1993년도 추계학술대회 논문집
• /
• pp.395-401
• /
• 1993

The purpose of this paper is to develop an automatic measuring system based on the digital image processing which can be applied to the in-process measurement of the characteristics of the thin thickness. The derivative operators is used for edge detection in gray level image. This concept can be easiliy illustrated with the aid of object shows an image of a simple light object on a dark background, the gray level profile along a horizontal scan line of the image, and the first and second derivatives of the profile. The first derivative of an edge modeled in this manner is () in all regions of constant gray level, and assumes a constant value during a gray level transition. The experimental results indicate that the developed qutomatic inspection system can be applied in real situation.

• 전자공학회논문지B
• /
• 제31B권3호
• /
• pp.91-102
• /
• 1994

For the analysis of textured image, it requires large storage space and computation time to calculate the matrix features such as SGLDM(Spatial Gray Level Dependence Matrix). NGLDM(Neighboring Gray Level Dependence Matrix). NSGLDM(Neighboring Spatial Gray Level Dependence Matrix) and GLRLM(Gray Level Run Length Matrix). In spite of a large amount of information that each matrix contains, a set of several correlated scalar features calculated from the matrix is not sufficient to approximate it. In this paper, we propose a new classifier for textured images based on these matrices in which the projected vectors of each matrix on the meaningful directions are used as features. In the proposed method, an unknown image is classified to the class of a known image that gives the maximum similarity between the projected model vector from the known image and the vector from the unknown image. In the experiment to classify images of agricultural products, the proposed method shows good performance as much as 85-95% of correct classification ratio.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제54권4호
• /
• pp.161-165
• /
• 2005

Need of a dimmer function becomes more important with increasing interest on a HDTV for home theater applications. In a conventional AC PDP, a possible method to reduce luminance of a whole Panel is to reduce a total number of sustain pulses and then to change the gray level. However, the reduction of the total sustain number causes the step of luminance to be rough. Moreover, it is impossible to control the luminance of the panel for a given gray level. In this paper, a simple and robust method is proposed to control linearly the luminance of whole panel by applying the asymmetric sustain pulses in the display period of the ADS driving scheme. As the range of luminance control by the proposed method is about $50\%$ for a given gray level. Moreover, it is experimentally verified that the proposed method shows similar dynamic margin performances compare with the conventional method.

• 한국정밀공학회지
• /
• 제12권6호
• /
• pp.72-79
• /
• 1995

The purpose of this paper is to develop an automatic measuring system based on the digital image processing which can be applied to the in-process measurment of the characteristics of the thin thickness. The derivative operators is used for edge detection in gray level image. This concept can be easily illustrated with the aid of object shows an image of a simple light object on a dark background, the gray level profile along a horizontal scan line of the image, and the first and second derivatives of the profile. The first derivative of an edge modeled in this manner is 0 in all regions of constant gray level, and assumes a constant value during a gray level transition. The experimental results indicate that the developed automatic inspection system can be applied in real situation.

• Agricultural and Biosystems Engineering
• /
• 제5권1호
• /
• pp.5-9
• /
• 2004

This study was carried out to develop methods of reducing the effect of solar illumination on pixel gray-levels of machine vision for agricultural field use. Two kinds of monochrome CCD cameras with manual and auto-iris lenses were used to take pictures within a range of 15 to 120 klux of solar illumination. A camera having more precise automatic control functions gave much better result. Four kinds of indices using pixel gray-level of the $99\%$ white DRS (diffuse reflectance standard) as a reference were tried to compensate pixel gray-levels of an image for variable illumination. Coefficients of variation of the indices within a range of illumination were used as a criterion for comparison. The study concluded that an index of (A+B)/A, where A is gray-level of the $99\%$ DRS and B is gray-level of the tested material, gave the best consistency in the range of solar illumination.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 1999년도 가을 학술발표논문집 Vol.26 No.2 (2)
• /
• pp.431-433
• /
• 1999

본 논문에서는 뇌의 자기공명(이하 MR로 줄임) 영상에서 양측 대뇌반구의 뇌백질과 뇌회백질의 추출에 관하여 연구하였다. MR 영상은 특정 장기에서 일정한 gray level 값을 유지하는 전산화단층촬영(이하 CT로 줄임) 영상과는 달리 사람마다 gray level 값이 다르며 한 사람에 대해서도 각 슬라이스에 따라 gray level 값이 다르므로 각 슬라이스별로 조직의 특성을 파악하여 백질과 회백질의 추출에 이용하였다. 먼저 뇌를 둘러싸고 있는 두피, 근육, 두개골과 함께 안구를 제거한 후 두 개강 내에 위치한 뇌간과 소뇌의 특성을 차례로 인식하여 대뇌반구로부터 분리한 후 제거하였다. 또한 추출된 대뇌의 영상으로부터 백질과 회백질의 체적을 구하고, 뇌신경게 진단방사선과 전문의의 manual 작업과 비교하여 본 논문에서 제시한 방법의 정확도를 검증하였다.

• 한국멀티미디어학회논문지
• /
• 제8권10호
• /
• pp.1347-1359
• /
• 2005

본 논문에서는 공간 명암도 의존 행렬을 이용하여 문서영상의 다양한 블록들을 상세하게 분류해 낼 수 있는 방법을 제안하였다. 제안한 블록분류 방법에서는 먼저 명암도 문서영상을 이진화하여 평활화 기법을 적용함으로써 명암도 영상의 질감특징을 이용하여 분할하는 것보다 신속하게 블록을 분할하고 동시에 그 위치정보도 구할 수 있도록 하였다. 분할된 각 블록들의 공간 명암도 의존 행렬로부터 문서블록들의 7가지 질감특징을 구하고, 이를 정규화한 다음 역전파 신경회로망를 이용하여 문서블록들을 분류하였다. 문서블록들을 큰 문자, 중간 문자, 작은 문자, 표, 그래픽 및 사진 등 여섯 가지 유형으로 상세 분류하였다. 또한 명암도 문서영상의 2차 통계 질감특징을 얻기 위해 공간 명암도 의존 행렬을 구할 때, 기존의 사진과 같은 일반 영상분할에서와는 달리, 문서블록 고유의 특징이 잘 반영되도록 하였다. 즉, 분할된 각 블록을 하나의 마스크로 정하여 수평 한 방향의 공간 명암도 의존 행렬을 구함으로써 고속의 질감특징추출과 상세 블록분류가 가능하도록 하였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
• /
• pp.77-80
• /
• 2000

In this paper, we present a new automatic thresholding algorithm based on maximum entropy of two-dimensional pixel histogram. While most of the previous algorithms select thresholds depending only on the histogram of gray level itself in the image, the presented algorithm considers 2D relational histogram of gray levels of two adjacent pixels in the image. Thus, the new algorithm tends to leave salient edge features on the image after thresholding. The experimental results show the good performance of the presented algorithm.