• Title/Summary/Keyword: anisotropic diffusion filter

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An Image Enhancement Method Using Modified Diffusion Function in Anisotropic Diffusion Filter (이방성 확산 필터에서 수정된 확산 함수를 이용한 영상 개선 방법)

  • Song, Young-Chul;Choi, Doo-Hyun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.1C
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    • pp.50-58
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    • 2004
  • An image enhancement method using modified anisotropic diffusion filter is proposed in this paper. It employs sensor noise estimation and scale space methods based on the minimum reliable scale. Then the anisotropic diffusion filter is modified by the calculated critical value function and local gradient. Through simulation, it is verified that the proposed algorithm has the capability of little or no noise amplification in homogenous region as well as superior edge enhancement.

A de-noising method based on connectivity strength between two adjacent pixels

  • Ye, Chul-Soo
    • Korean Journal of Remote Sensing
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    • v.31 no.1
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    • pp.21-28
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    • 2015
  • The essential idea of de-noising is referring to neighboring pixels of a center pixel to be updated. Conventional adaptive de-noising filters use local statistics, i.e., mean and variance, of neighboring pixels including the center pixel. The drawback of adaptive de-noising filters is that their performance becomes low when edges are contained in neighboring pixels, while anisotropic diffusion de-noising filters remove adaptively noises and preserve edges considering intensity difference between neighboring pixel and the center pixel. The anisotropic diffusion de-noising filters, however, use only intensity difference between neighboring pixels and the center pixel, i.e., local statistics of neighboring pixels and the center pixel are not considered. We propose a new connectivity function of two adjacent pixels using statistics of neighboring pixels and apply connectivity function to diffusion coefficient. Experimental results using an aerial image corrupted by uniform and Gaussian noises showed that the proposed algorithm removed more efficiently noises than conventional diffusion filter and median filter.

Image Quality Improvement in Computed Tomography by Using Anisotropic 2-Dimensional Diffusion Based Filter (비등방성 2차원 확산 기반 필터를 이용한 전산화단층영상 품질 개선)

  • Seoung, Youl-Hun
    • Journal of the Korean Society of Radiology
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    • v.10 no.1
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    • pp.45-51
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    • 2016
  • The purpose of this study was tried to remove the noise and improve the spatial resolution in the computed tomography (CT) by using anisotropic 2-dimensional (2D) diffusion based filter. We used 4-channel multi-detector CT and american association of physicists in medicine (AAPM) phantom was used for CT performance evaluation to evaluate the image quality. X-ray irradiation conditions for image acquisition was fixed at 120 kVp, 100 mAs and scanned 10 mm axis with ultra-high resolution. The improvement of anisotropic 2D diffusion filtering that we suggested firstly, increase the contrast of the image by using histogram stretching to the original image for 0.4%, and multiplying the individual pixels by 1.2 weight value, and applying the anisotropic diffusion filtering. As a result, we could distinguished five holes until 0.75 mm in the original image but, five holes until 0.40 mm in the image with improved anisotropic diffusion filter. The noise of the original image was 46.0, the noise of the image with improved anisotropic 2D diffusion filter was decreased to 33.5(27.2%). In conclusion improved anisotropic 2D diffusion filter that we proposed could remove the noise of the CT image and improve the spatial resolution.

Micro-crack Detection in Silicon Solar Wafer through Optimal Parameter Selection in Anisotropic Diffusion Filter (비등방 확산 필터의 최적조건 선정을 통한 태양전지 실리콘 웨이퍼의 마이크로 크랙 검출)

  • Seo, Hyoung Jun;Kim, Gyung Bum
    • Journal of the Semiconductor & Display Technology
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    • v.13 no.3
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    • pp.61-67
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    • 2014
  • Micro-cracks in crystalline silicon wafer often result in wafer breakage in solar wafer manufacturing, and also their existence may lead to electrical failure in post fabrication inspection. Therefore, the reliable detection of micro-cracks is of importance in the photovoltaic industry. In this paper, an experimental method to select optimal parameters in anisotropic diffusion filter is proposed. It can reliably detect micro-cracks by the distinct extension of boundary as well as noise reduction in near-infrared image patterns of micro-cracks. Its performance is verified by experiments of several type cracks machined.

Image Enhancement of Image Intensifying Device in Extremely Low-Light Levels using Multiple Filters and Anisotropic Diffusion (다중필터와 이방성 확산을 이용한 극 저조도 조건에서의 미광증폭장비 영상 개선)

  • Moon, Jin-Kyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.7
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    • pp.36-41
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    • 2018
  • An image intensifying device is equipment that makes weak objects visible in a dark environment, such as making nighttime bright enough to let objects be visually observed. It is possible to obtain a clear image by amplifying the light in the presence of a certain amount of weak light. However, in an extremely low-light environment, where even moonlight is not present, there is not enough light to amplify anything, and the sharpness of the screen deteriorates. In this paper, a method is proposed to improve image quality by using multiple filters and anisotropic diffusion for output noise of the image-intensifying device in extreme low-light environments. For the experiment, the output of the image-intensifying device was obtained under extremely low-light conditions, and signal processing for improving the image quality was performed. The configuration of the filters for signal processing uses anisotropic diffusion after applying a median filter and a Wiener filter for effective removal of salt-and-pepper noise and Gaussian noise, which constitute the main noise appearing in the image. Experimental results show that the improvement visually enhanced image quality. Both peak signal-to-noise ratio (PSNR) and SSIM, which are quantitative indicators, show improved values.

Asymmetric channel model for a perpendicular magnetic recording system with a ring-head (Ring-헤드를 갖는 수직 자기기록 시스템을 위한 비대칭 채널 모델)

  • Lee, Joo-Hyun;Lee, Jae-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.1C
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    • pp.45-49
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    • 2004
  • An image enhancement method using modified anisotropic diffusion filter is proposed in this paper. It employs sensor noise estimation and scale space methods based on the minimum reliable scale. Then the anisotropic diffusion filter is modified by the calculated critical value function and local gradient. Through simulation, it is verified that the proposed algorithm has the capability of little or no noise amplification in homogenous region as well as superior edge enhancement.

Inverse halftoning Using Anisotropic diffusion and Edge map (비등방성 확산 필터와 에지맵을 이용한 역하프토닝)

  • 고기영;주동현;염동훈;김두영
    • Proceedings of the Korea Institute of Convergence Signal Processing
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    • 2000.12a
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    • pp.81-84
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    • 2000
  • Digital Halftoning convert a continuous-tone images to a binary images. Inverse halftoning addresses the problem of recovering a continuous image from a halftoned binary image. Simple low pass filtering can remove the high frequency noise but it also removes the edge information. Thus the edge information should be separated from the halftoning noise. As a result, the edge of result image is blurring. This paper present that we obtain continuous-tone-image which using Anisotropic diffusion filter. To reduce noise without blurring the edges of reconstructed image use edge map. The experimental results show that proposed method gives a higher PSNR and better subjective quality than conventional methods. As a result, the edge information of reconstructed image reduce blurring.

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A Noisy-Robust Approach for Facial Expression Recognition

  • Tong, Ying;Shen, Yuehong;Gao, Bin;Sun, Fenggang;Chen, Rui;Xu, Yefeng
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.4
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    • pp.2124-2148
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    • 2017
  • Accurate facial expression recognition (FER) requires reliable signal filtering and the effective feature extraction. Considering these requirements, this paper presents a novel approach for FER which is robust to noise. The main contributions of this work are: First, to preserve texture details in facial expression images and remove image noise, we improved the anisotropic diffusion filter by adjusting the diffusion coefficient according to two factors, namely, the gray value difference between the object and the background and the gradient magnitude of object. The improved filter can effectively distinguish facial muscle deformation and facial noise in face images. Second, to further improve robustness, we propose a new feature descriptor based on a combination of the Histogram of Oriented Gradients with the Canny operator (Canny-HOG) which can represent the precise deformation of eyes, eyebrows and lips for FER. Third, Canny-HOG's block and cell sizes are adjusted to reduce feature dimensionality and make the classifier less prone to overfitting. Our method was tested on images from the JAFFE and CK databases. Experimental results in L-O-Sam-O and L-O-Sub-O modes demonstrated the effectiveness of the proposed method. Meanwhile, the recognition rate of this method is not significantly affected in the presence of Gaussian noise and salt-and-pepper noise conditions.

Automatic Left Ventricle Segmentation using Split Energy Function including Orientation Term from CTA

  • Kang, Ho Chul
    • International journal of advanced smart convergence
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    • v.7 no.2
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    • pp.1-6
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    • 2018
  • In this paper, we propose an automatic left ventricle segmentation method in computed tomography angiography (CTA) using separating energy function. First, we smooth the images by applying anisotropic diffusion filter to remove noise. Secondly, the volume of interest (VOI) is detected by using k-means clustering. Thirdly, we divide the left and right heart with split energy function. Finally, we extract only left ventricle from left and right heart with optimizing cost function including orientation term.

Convergence Analysis on Bilateral Filter with a Fixed Point Iteration (고정점 반복을 이용한 양방향 필터의 수렴 분석)

  • Ham, Bumsub;Sohn, Kwanghoon
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2011.07a
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    • pp.11-13
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    • 2011
  • 양방향 필터 (Bilateral filter)는 에지 보전 평활화 필터로써 디노이징, 반사 제거, 스테레오 매칭 등 다양한 분야에서 사용되고 있다. 이는 기존의 가우시안 필터에 사용되는 공간 도메인 커널 (spatial kernel)이외에 강도 도메인 커널 (range kernel)을 추가로 사용하여 비슷한 강도의 픽셀에 높은 가중치를 부여함으로써 에지를 보전하면서 평활화를 한다. 또한 양방향 필터는 비등방성 확산 필터 (Anisotropic diffusion filter)와 달리 항상 수렴을 보장한다. 따라서 본 논문에서는 고정점 반복 이론을 적용하여 양방향 필터의 수렴을 수학적으로 증명한다.

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