• International journal of advanced smart convergence
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• 제7권4호
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• pp.108-113
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• 2018

In this study, we introduce a new image gradient computation based on understanding of image generation. Most images consist of groups of pixels with similar color information because the images are generally obtained by taking a picture of the real world. The general gradient operator for an image compares only the neighboring pixels and cannot obtain information about a wide area, and there is a risk of falling into a local minimum problem. Therefore, it is necessary to attempt to introduce the gradient operator of the interval concept. We present a bow-tie gradient by color values of pixels on bow-tie region of a given pixel. To confirm the superiority of our study, we applied our bow-tie gradient to image segmentation algorithms for various images.

• 융합신호처리학회논문지
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• 제12권2호
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• pp.91-95
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• 2011

In this paper, we present an improved multi-scale gradient algorithm. The proposed algorithm works the effectively handling of both step and blurred edges. In the proposed algorithm, the image sharpening operator is sharpening the edges and contours of the objects. This operation gives an opportunity to get noise reduced image and step edged image. After that, multi-scale gradient operator works on noise reduced image in order to get a gradient image. The gradient image is segmented by watershed transform. The approach of region merging is used after watershed transform. The region merging is carried out according to the region area and region homogeneity. The region number of the proposed algorithm is 36% shorter than that of the existing algorithm because the proposed algorithm produces a few irrelevant regions. Moreover, the computational time of the proposed algorithm is relatively fast in comparison with the existing one.

• 한국지능시스템학회논문지
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• 제11권6호
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• pp.454-458
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• 2001

이 논문에서는 디지털 영상의 퍼지 시스템 표현으로부터 유도된 Edge 검출 알고리듬에 대하여 기술한다. 이 알고리듬은 Gradient을 기반으로 한 것으로 Convolution Kernel이 기존의 Roberts, Prewitt 또는 Sobel등이 제안한 Gradient Kernel과 다른 새로운 것이다. 사용한 퍼지시스템은 디지털 영상을 근사적으로 표현한 Bicubic Spline 함수를 퍼지시스템 화한것으로서 2차 도함수가 연속이기 때문에 Gradient나 Laplacian 연산이 가능하다. Grid 점들에서 이 함수의 Gradient는 두 개의 축 방향으로 각각 한개의 3$\times$3행렬과 영상과의 Covolution에 의하여 산출됨을 보였으며 이를 이용하여 검출된 Edge들은 기존의 다른 방법을 사용하여 검출된 Edge 영상보다 훨씬 선명함을 확인하였다. 이 알고리듬 적용사례 2개에 대한 기술에 포함되어 있다.

• 대한전자공학회논문지
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• 제24권1호
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• pp.97-101
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• 1987

The edge, a discontinuity or abrupt change in the gray-level or color, is a fundamentally important primitive feature of an image necessary for the image analysis and classification. Two-dimensional 3x3 compass gradient operators (ex. Sobel, Prewitt, and Kirsch operators)are commonly used in the edge detection and usually detect 8 compass directional components. In this paper, we present a new interpretation of the relationships between the resulting 8 gradient magnitudes and the 8 intensity values of neighboring pixels which are covered by the two-dimensional 3x3 mask. It is expected that a new gradient edge operator may be designed by changing the eigenvalues in the transform domain and the fast optical edge operator may be implemented by using the optical system.

• Journal of Advanced Marine Engineering and Technology
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• 제24권2호
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• pp.82-89
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• 2000

에지검출은 영상인식의 첫 단계임을 동시에 영상인식의 성능을 좌우하는 아주 중요한 단계이다. 기존의 기울기연산자나 표면접합에 의한 에지검출과 달리 본 논문에서는 에지의 영역정보를 이용한 에지검출 알고리즘을 제시한다. 먼저 에지의 적합한 위치, 에지의 두께 그리고 에지의 길이에 대한 정의를 제시하고, 제시된 에지정의를 기본으로한 12개의 에지검출 윈도우와 알고리즘을 제안하였다. 제안된 12개의 윈도우는 모든 형태의 에지를 추출할 수 있는 에지검출윈도우로써 일반적으로 많이 사용되고 있는 기울기 연산자나 0점교차 연산자인 LoG 연산자보다 좋은 에지검출 성능을 보여 주었다.

• 전자공학회논문지C
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• 제34C권4호
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• pp.36-44
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• 1997

An efficient context-free multiple-object segmentation using attention operator based on modified generalized symmetry transform is proposed and implemented by modifying a radial basis function network. By using the difference of intensity gradient, instead of te intensity gradient itself, in generalized symmetry tranform so as to make the attention operator to preserve the edges of the objects shape, an efficient context-free multiple-object segementation is proposed in which no a priori shape informtion on the objects is requried. The attention operator is implemented by using a modified radial basis function network which can reflect symmetry, and by using te edge pyramid of the input image, both of the local and the global symmetry of the objects are reflected simultaneously to make the multiple-object with different sizes be segmented with a singel fixed-size $n\timesm$ can be done with O(n) complexity. The simulaton results show that the proposed algorithm can efficiently be used in context-free multiple-object segmentation even for the low contrast IR images as well as for the images from the camera.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제3권1호
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• pp.1-15
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• 1999

Gradient recovery techniques for the second order elliptic boundary value problem are well known. In particular, the Midpoint and the Vertex Recovery Operator have been studied by various authors and under suitable assumptions on the regularity of the unknown solution superconvergence property of these recovered gradients have been proved. In this paper we extend these results to the recovered gradient of the finite element approximation to a model initial-boundary value problem, and go on to prove superconvergence result for this recovered gradient in a discrete (in time) error norm.

• Journal of the Optical Society of Korea
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• 제15권1호
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• pp.15-21
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• 2011

This paper proposes a new approach to palmprint verification based on the gradient, in which a palm image is considered to be a three-dimensional terrain. Principal lines and wrinkles make deep and shallow valleys on a palm landscape. Then the steepest slope direction in each local area is first computed using the Kirsch operator, after which an orientation map is created that represents the dominant slope direction of each pixel. In this study, three orientation maps were made with different scales to represent local and global gradient information. Next, feature matching based on pixel-unit comparison was performed. The experimental results showed that the proposed method is superior to several state-of-the-art methods. In addition, the verification could be greatly improved by fusing orientation maps with different scales.

• 한국측량학회지
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• 제9권2호
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• pp.139-149
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• 1991

일반적으로 수치표고모델은 데이타 획득의 자동화 및 관리가 용이한 격자망의 형태로 구성되어져 왔다. 그러나 격자형 수치표고모델은 일정한 간격으로 데이타를 추출하기 때문에 지형의 특성을 정확하고 상세하게 나타내기 위하여는 많은 데이타 용량을 필요로 한다. 본 연구는 격자형 수치표고모델로부터 지형을 대표할 수 있는 중심점을 추출함으로써 압축된 수치표고 모델을 구축하고자 하였다. 이를 위하여 지형의 중심점이 1차미분 연산자 및 라플라스 연산자에 의한 하이-패스 필터링에 의하여 추적되어 진다. 본 연구의 결과 압축된 수치표고모델을 구축하는데 있어서 라플라스 연산자가 1차미분 연산자보다 더 효과적인 하이-패스 필터임을 알 수 있었다.

• 한국생산제조학회지
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• 제7권6호
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• pp.49-56
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• 1998

Super precision working technique and machine tool have been continually developed thanks to advanced electronic field. To obtain good result. it is necessary to investigate surface in grinding with $mu extrm{m}$ level. There were quite many researches to satisfy these demands by using non-contact methods through the computer vision. In this study, the texture of working surface was analyzed. co-occurrence matrices was obtained from the surface roughness. Texture parameter was obtained using position operator composed of $ heta$, d according to variation of angle direction and distance. As a result, it was found that surface texture was more affected by direction($\theta$) than distance(d).