• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.37-39
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• 2012

최근 ToF(Time-of-Flight) 방식의 깊이 센서 카메라가 깊이 영상 획득에 많이 사용되고 있다. 그러나 ToF 깊이 카메라가 제공하는 깊이 영상은 센서의 물리적 한계로 인해 잡음이 존재한다. 따라서 고품질의 깊이 영상을 얻기 위해서는 깊이 영상의 잡음을 제거해 주는 것이 필수적이다. 일반적으로 깊이 영상의 잡음 제거에는 joint bilateral filter 를 사용한다. Joint bilateral filter 는 기준 화소와 그 주변 화소의 색상 영상의 밝기 차이값과 화소간 거리값에 각각 가우시안 함수를 적용하여 joint histogram 을 생성하고 그 평균값을 기준 화소의 깊이값으로 채운다. 하지만 이 과정에서 깊이 영상의 경계 영역에서 흐려짐 현상이 발생한다. 경계영역에 발생한 흐려짐 현상은 최종적인 3D 입체 콘텐츠의 품질을 저하시킨다. 본 논문에서는 이와 같은 문제점을 해결하기 위해 joint histogram 의 최고점을 찾아 기준 화소의 깊이값을 채우는 기법을 제안한다. 최고점 탐색을 통해 기존 기법의 평균값을 통해 생기는 흐려짐 현상을 줄이고 깊이 영상의 경계를 보존하면서 잡음을 제거하였다. 실험을 통하여 제안하는 기법의 우수성을 확인하였다.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.1048-1060
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• 2012

In this paper, an adaptive temporal and spatial filter (ATSF) based on mean square error (MSE) estimation is proposed. ATSF is a block based de-noising algorithm. Each noisy block is selectively filtered by a temporal filter or a spatial filter. Multi-hypothesis motion compensated filter (MHMCF) and bilateral filter are chosen as the temporal filter and the spatial filter, respectively. Although there is no original video, we mathematically derivate a formular to estimate the real MSE between a block de-noised by MHMCF and its original block and a linear model is proposed to estimate the real MSE between a block de-noised by bilateral filter and its original block. Finally, each noisy block is processed by the filter with a smaller estimated MSE. Simulation results show that our proposed algorithm achieves substantial improvements in terms of both visual quality and PSNR as compared with the conventional de-noising algorithms.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1528-1531
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• 2013

본 논문은 스테레오 시각에서 3차원 정보를 얻기 위해 bilateral filter를 이용한 그래프 컷 기반의 다해상도 스테레오 영상 정합 방법을 제안하고자 한다. 제안한 방법은 변위도에서 물체의 경계를 명확히 구분하기 위해 bilateral filter를 이용하여 그래프의 각 노드들을 연결하는 경로의 가중치를 결정하고 정합 비용을 통합한다. 정합 과정에서 계산복잡도를 줄이기 위해 계층적 다해상도 구조를 적용하여 영상 피라미드를 만들고, 정합의 정확성을 향상시키기 위해 정합 영역에 변위 평활성과 같은 제약 조건을 적용하여 변위를 전파하는 방법을 사용한다. 실험을 통해 제안한 방법이 변위 탐색 시간을 감소시킬 뿐만 아니라 기존의 그래프 컷의 단점을 보완할 수 있음을 확인하고자 한다.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.565-571
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• 2012

During depth data acquisition and transmission, the quality of depth maps is usually degraded by physical noise and coding error. In this paper, a new joint bilateral filter based on the common distance transform is presented to enhance the low-quality depth map. The proposed method determines the amount of exploitable color data according to distance transform values of depth and color pixels. Consequently, the proposed filter minimizes noise in the depth map while suppressing visual artifacts of joint bilateral filtering. Experimental results show that our method outperforms other conventional methods in terms of noise reduction and visual artifact suppression.

• Nuclear Engineering and Technology
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• v.39 no.6
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• pp.725-730
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• 2007

This paper describes recently developed techniques for effective filtering of neutron detector signal noise. In this paper, three kinds of noise filters are proposed and their performance is demonstrated for the estimation of reactivity. The tested filters are based on the unilateral kernel filter, unilateral kernel filter with adaptive bandwidth and bilateral filter to show their effectiveness in edge preservation. Filtering performance is compared with conventional low-pass and wavelet filters. The bilateral filter shows a remarkable improvement compared with unilateral kernel and wavelet filters. The effectiveness and simplicity of the unilateral kernel filter with adaptive bandwidth is also demonstrated by applying it to the reactivity measurement performed during reactor start-up physics tests.

• Journal of Korea Multimedia Society
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• v.22 no.1
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• pp.10-17
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• 2019

In High Dynamic Range (HDR) image processing, tone mapping is the process to compress an input image into a Low Dynamic Range (LDR) image. In most cases, the reason that detail preservation is prior to take over tone mapping is that the dynamic range is significantly different between input and output images. In the case of iCAM06, details are separated by using a bilateral filter, however, it causes noise amplification at the dim surround region. Thus, we suggest that the detail signal, which is separated from the bilateral filter, is combined with the base signal after an adaptive Kalman filter is applied according to the local standard deviation. We confirmed that the proposed method enhances the HDR images quality by checking the noise reduction in a dim surround region.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1844-1850
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• 2016

The bilateral filter can reduce the noise while preserving details computing the filtering output at each pixels as the average of neighboring pixels. In this paper, we propose a real-time system based on window division. Overall performance is increased due to the parallel architectures which computes five rows in the kernel window simultaneously but with pipelined scheduling. We consider the tradeoff between the filter performance and the hardware cost and the bit allocation has been determined by PSNR analysis. The proposed architecture is designed with verilogHDL and synthesized using Dongbu Hitek 110nm standard cell library. The proposed architecture shows 416Mpixels/s (397fps) of throughput at 416MHz of operating frequency with 132K gates.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.350-357
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• 2010

In this paper, we present an auto-range fast bilateral filter (FBF) for high-dynamic-range (HDR) images, which increases computation speed by using adaptive standard deviations for range filter (RF) of FBF in iCAM06. Many images that cover the entire dynamic range of the scene with different exposure times are fused into one High Dynamic Range (HDR) image. The representative algorithm for HDR image rendering is iCAM06, which is based on the iCAM framework, such as the local white point adaptation, chromatic adaptation, and the image processing transform (IPT) uniform color space. FBF in iCAM06 uses constant standard deviation in RF. So, it causes unnecessary FBF computation in high stimulus range with broad and low distribution. To solve this problem, the low stimulus image and high stimulus image of CIE tri-stimulus values (XYZ) divided by the threshold are respectively processed by adaptive standard deviation based on its histogram distribution. Experiment results show that the proposed method reduces computation time than the previous FBF.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.105-107
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• 2012

본 논문에서는 영상의 잡음제거에 주로 적용되어 왔던 양방향 필터(bilateral filter) 기법을 개량하여 에지 정보를 더 잘 살리게 하는 방법을 제안한다. 우선, 잡음 영상에서 에지의 위치를 파악하기 위한 방법으로, 이웃픽셀값들의 분산을 이용하는 방법을 제안한다. 또한 에지와의 거리를 기반으로 필터의 계수를 조정하는 방법을 제시한다. 따라서 제안하는 알고리즘을 적용하여 잡음 제거를 수행하면 기존의 잡음 제거율을 유지하면서도 에지정보를 보존한 결과를 얻을 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.3166-3179
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• 2013

A pre-processing system for adaptive noise removal is proposed based on the principle of identifying and filtering object regions and background regions. Human perception of images depends on bright, well-focused object regions; these regions can be treated with the best filters, while simpler filters can be applied to other regions to reduce overall computational complexity. In the proposed method, bright region segmentation is performed, followed by segmentation of object and background regions. Noise in dark, background, and object regions is then removed by the median, fast bilateral, and bilateral filters, respectively. Simulations show that the proposed algorithm is much faster than and performs nearly as well as the bilateral filter (which is considered a powerful noise removal algorithm); it reduces computation time by 19.4 % while reducing PSNR by only 1.57 % relative to bilateral filtering. Thus, the proposed algorithm remarkably reduces computation while maintaining accuracy.