• Title/Summary/Keyword: Image Gradient

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A Feature Vector Generation Technique through Gradient Correction of an Outline in the Mouth Region (입 영역에서 외곽선의 기울기 보정을 통한 특징벡터 생성 기법)

  • Park, Jung Hwan;Jung, Jong Jin;Kim, Guk Boh
    • Journal of Korea Multimedia Society
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    • v.17 no.10
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    • pp.1141-1149
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    • 2014
  • Recently, various methods to effectively eliminate the noise are researched in image processing techniques. However, the conventional noise filtering techniques, which remove most of the noise, are less efficient for remained noise detection after filtering due to exploiting no face feature information. In this paper, we proposed a feature vector generation technique in the mouth region by distinguishing and revising the remained noise through gradient correction, when the outline is extracted after performing noise filtering.

Palmprint Verification Using Multi-scale Gradient Orientation Maps

  • Kim, Min-Ki
    • Journal of the Optical Society of Korea
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    • v.15 no.1
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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.

Multi-sensor Image Registration Using Normalized Mutual Information and Gradient Orientation (정규 상호정보와 기울기 방향 정보를 이용한 다중센서 영상 정합 알고리즘)

  • Ju, Jae-Yong;Kim, Min-Jae;Ku, Bon-Hwa;Ko, Han-Seok
    • Journal of the Korea Society of Computer and Information
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    • v.17 no.6
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    • pp.37-48
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    • 2012
  • Image registration is a process to establish the spatial correspondence between the images of same scene, which are acquired at different view points, at different times, or by different sensors. In this paper, we propose an effective registration method for images acquired by multi-sensors, such as EO (electro-optic) and IR (infrared) sensors. Image registration is achieved by extracting features and finding the correspondence between features in each input images. In the recent research, the multi-sensor image registration method that finds corresponding features by exploiting NMI (Normalized Mutual Information) was proposed. Conventional NMI-based image registration methods assume that the statistical correlation between two images should be global, however images from EO and IR sensors often cannot satisfy this assumption. Therefore the registration performance of conventional method may not be sufficient for some practical applications because of the low accuracy of corresponding feature points. The proposed method improves the accuracy of corresponding feature points by combining the gradient orientation as spatial information along with NMI attributes and provides more accurate and robust registration performance. Representative experimental results prove the effectiveness of the proposed method.

Performance Analysis of Adaptive Corner Shrinking Algorithm for Decimating the Document Image (문서 영상 축소를 위한 적응형 코너 축소 알고리즘의 성능 분석)

  • Kwak No-Yoon
    • Journal of Digital Contents Society
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    • v.4 no.2
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    • pp.211-221
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    • 2003
  • The objective of this paper is performance analysis of the digital document image decimation algorithm which generates a value of decimated element by an average of a target pixel value and a value of neighbor intelligible element to adaptively reflect the merits of ZOD method and FOD method on the decimated image. First, a target pixel located at the center of sliding window is selected, then the gradient amplitudes of its right neighbor pixel and its lower neighbor pixel are calculated using first order derivative operator respectively. Secondly, each gradient amplitude is divided by the summation result of two gradient amplitudes to generate each local intelligible weight. Next, a value of neighbor intelligible element is obtained by adding a value of the right neighbor pixel times its local intelligible weight to a value of the lower neighbor pixel times its intelligible weight. The decimated image can be acquired by applying the process repetitively to all pixels in input image which generates the value of decimated element by calculating the average of the target pixel value and the value of neighbor intelligible element. In this paper, the performance comparison of proposed method and conventional methods in terms of subjective performance and hardware complexity is analyzed and the preferable approach for developing the decimation algorithm of the digital document image on the basis of this analysis result has been reviewed.

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Estimation of Storage Capacity using Topographical Shape of Sand-bar and High Resolution Image in Urban Stream (도시하천의 지형태 자료와 영상정보를 이용한 수체적 시험평가)

  • Lee, Hyun Seok;Lee, Geun Sang
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.3D
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    • pp.445-450
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    • 2008
  • Recently, environmental and ecological approaches is in progress in urban stream, especially the guarantee of instream flow becomes very important. In this paper, it is suggested that water volume estimation method utilizing the topographical shape data obtained by field investigation and satellite image to manage the urban stream efficiently. The data obtained at Gap River is the study area are analysed and those results are as belows. First, surveying to investigate topographic shape characteristics of urban stream is carried out. In details, the gradient characteristics from water surface to bottom in case of sand area and in case of grass area are 0.013 and 0.065 respectively. In conclusion, the gradient characteristic of grass area is five times bigger than that of sand area. Besides, IKONOS image is classified by spectrum analysis and Minimum Distance Method and the sand area extraction method by the generalization method as Median filter is suggested to calculate water volume. Finally, mapping process on the sand area extracted from the topographical shape field data in river and satellite images is carried out by the GIS spatial analysis. And on the assumption that the water level was 1m at that time when satellite image was taken, the water volume was $225,258m^3$. It is clarified that the effect of water volume improvement was about 10.5% in comparison with water volume that had no consideration on the gradient characteristics of sand-bar.

Color Image Segmentation Using Characteristics of Superpixels (슈퍼픽셀특성을 이용한 칼라영상분할)

  • Lee, Jeong-Hwan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.05a
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    • pp.649-651
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    • 2012
  • In this paper, a method of segmenting color image using characteristics of superpixels is proposed. A superpixel is consist of several pixels with same features such as luminance, color, textures etc. The superpixel can be used for image processing and analysis with large scale image to get high speed processing. A color image can be transformed to $La^*b^*$ feature space having good characteristics, and the superpixels are grouped by clustering and gradient-based algorithm.

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Application Study on the View Points Analysis for National Roads Route using Digital Elevation Data

  • Yeon, Sang-Ho;Hong, Ill-Hwa
    • Proceedings of the KSRS Conference
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    • 2002.10a
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    • pp.292-296
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    • 2002
  • This study has been accomplished as a experimental study for field application of 3D Perspective Image Map creation using Digital Topographical Map and based on the Ortho-Projection Image which is generated from Satellite Overlay Images and the precise Relative Coordinates of longitude, latitude and altitude which is corrected by GCP(Ground Control Point). AS to Contour Lines Map which is created by Coordinate conversion of 1:5,000 Topographical Map, we firstly made Satellite Image Map to substitute for Digital Topographical Map through overlapping the original images on top of each Ortho-Projection Image created and checking the accuracy. In addition to 3D Image Map creation for 3D Terrain analysis of a target district, Slope Gradient Analysis, Aspect Analysis and Terrain Elevation Model generation, multidirectional 3D Image generation by DEM can be carried out through this study. This study is to develop a mapping technology with which we can generate 3D Satellite Images of a target district through the composition of Digital Maps and Facility Blueprint and arbitrarily create 3D Perspective Images of the target district from any view point.

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Edge Detection of Ultrasonic Image Using Neighhood Mean Intensity Difference (주변 평균 밝기차를 이용한 초음파 영상의 에지 검출)

  • Won, Chul-Ho;Koo, Sung-Mo;Kim, Myoung-Nam;Cho, Jin-Ho
    • Proceedings of the KOSOMBE Conference
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    • v.1994 no.05
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    • pp.23-26
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    • 1994
  • A new algorithm using a measure for edge detection from ultrasonic image is proposed. Ultrasonic image is blurred by pre-processing for removing speckle noises and precise edge placement is not clear. Because extracted edge from blurred image is thick, a measure utilizing the absolute difference of mean between two windows is used to thin the thickness of extracted edge in blurred image. The algorithm is effective to process blurred image due to the noise filtering that remove speckle noises. Results of the proposed algorithm using a measure show good edge detection performance comparing with other gradient edge operators.

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Image segmentation preserving semantic object contours by classified region merging (분류된 영역 병합에 의한 객체 원형을 보존하는 영상 분할)

  • 박현상;나종범
    • Proceedings of the IEEK Conference
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    • 1998.06a
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    • pp.661-664
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    • 1998
  • Since the region segmentation at high resolution contains most of viable semantic object contours in an image, the bottom-up approach for image segmentation is appropriate for the application such as MPEG-4 which needs to preserve semantic object contours. However, the conventioal region merging methods, that follow the region segmentation, have poor performance in keeping low-contrast semantic object contours. In this paper, we propose an image segmentation algorithm based on classified region merging. The algorithm pre-segments an image with a large number of small regions, and also classifies it into several classes having similar gradient characteristics. Then regions only in the same class are merged according to the boundary weakness or statisticsal similarity. The simulation result shows that the proposed image segmentation preserves semantic object contours very well even with a small number of regions.

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Image Focal Pont Usig Modified Mask Processing (변형 마스크 프로세싱을 이용한 영상초점 판별)

  • 이훈주
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.04a
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    • pp.127-132
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    • 2000
  • Though the increment of using computer vision system, there are lots of difficulties to measure precisely because of measurement error or distortion phenomenon. Among these reasons, the distortion of edge is dominant reason which is occurred by the blurred image. So, the problem of clear judgment about image focal point is very important. We must fix the discrimination criteria which is collected by image recognition of precise focus. To solve these problems, we compare with make processing methods using image intensity gradient, laplacian, and sum -modified laplacian operator. These experimental results showed modified mask processing method is effective.

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