• Journal of Korea Multimedia Society
• /
• v.5 no.2
• /
• pp.147-157
• /
• 2002

Noise in image sequences is visually offensive and may mask important image detail. In addition to degradation of visual quality, the noise pattern increases the entropy of the image, and thus hinders effective compression. This paper proposes a spatial and a temporal joint filters to reduce the noise by jointly connecting two adaptive noise reducers with different characteristics, and we also propose an IIR-type 3D noise reduction litter scheme connecting the spatial and the temporal joint filters. The proposed 3D IIR filter not only strongly removes noise in uniform image regions while preserving edges and details but also effectively suppresses temporal flicker caused by noise. Experimental results show that the proposed scheme improves subjective quality as well as objective quality as compared with the various noise filtering techniques.

• 한국HCI학회:학술대회논문집
• /
• 2006.02a
• /
• pp.807-811
• /
• 2006

본 논문에서는 기존의 연구에서 여러 단계를 거쳐 복잡한 연산을 한 후에 수묵화 표현이 가능했던 것과 달리 기존에 요구되었던 채색과정을 줄임으로써 렌더링의 효율을 높인 실시간 3차원 수묵화 기법을 제안한다. 본 논문에서 제안된 기법은 모델이 보여지는 방향에 따라 다른 조명 값과 법선 벡터 값을 계산한 후 연산 값에 따라서 여러장의 텍스처를 일정 비율에 맞춰서 모델에 적용함으로써 수묵화의 특징인 농담, 발묵 효과를 한 번에 적용할 수 있게 한다. 그리고 모델의 윤곽선을 표현하는데 사용자의 입력에 따라 붓의 굵기를 조절하게 하여 보다 사실적인 수묵화 느낌을 살렸다. 또한 텍스처 매핑 이후 에도 동양화적인 느낌을 살리기 위해서 두 가지의 종이질감효과를 추가하였다. 이 2 가지의 종이질감 효과는 일종의 안개 필터로서 기존의 안개 필터와 달리 모델이 그려지는 위치에 따라서 각각 가중치가 다른 필터가 적용되게 하였다. 이렇게 필터가 적용된 렌더링의 결과는 일반적으로 채색된 3차원 모델과 느낌이 다른 자연스러운 결과를 생성할 수 있다. 본 연구는 또한 간단한 구현에 장점을 두고 있기 때문에 간단한 애니메이션이나 일반 3차원 게임 등 여러 분야에서 기존에 적용하기 어려웠던 수묵화 기법을 다양하게 활용할 수 있는 가능성을 제시한다.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.32 no.12
• /
• pp.427-434
• /
• 1983

Singular Value Decomposition of 2-D Finite Impulse Response was used to design a variable cutoff 2-D FIR filters. Basically this approach allows to use 1-D techniques while dealing with 2-D filters. In this paper, our aim is to provide away of easily tuning 2-D FIR filters. For example, one would like to adjust interactively the cutoff frequency of a 2-D Circular Symmetric low-pass filter on an image processing system. The decomposition of 2-D FIR filters along with techniques available for tuning 1-D FIR filters allows such adjustment. Several design examples are shown.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.10a
• /
• pp.522-527
• /
• 2000

본 논문은 그레이이미지를 컬러이미지로 변환하는 의사칼라이미지 향상에 관한 연구이다. 적용기법은 그레이이미지의 시간영역신호를 주파수영역으로 변환하고 LPF, BPF, HPF 2차원필터를 통과시켜 시간영역으로 역 변환한 후 각각에 대해 히스토그램 평활화하여 RGB 신호를 구하는 과정에서 의사 칼라를 얻는다. 실험 결과 필터주파수가 증가함에 따라 PSNR도 증가하고 낮게 설정하면 경계부분의 화질이 좋아진다. 2차원 주파수필터의 사용은 칼라 변환 시 강조하고자 하는 부분을 보다 자유롭게 변환할 수 있고 다양한 컬러 이미지로 향상되어 영상분석에 효과가 있다. 의사칼라의 변환에 의한 식별 인식능력은 9dB 정도 향상된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.99-100
• /
• 2015

Digital image blur occurs due to various environmental conditions at the time of shooting. Blur produces the low-frequency component in the image. This problem worsens the quality of the digital image. To address this issue, contrast improvement methods has been widely studied. 2D filter to enhance the edges is a simple structure with a fast processing speed. However, the sensitivity of the human visual system is different depending on the surrounding brightness locally. Thus, in this paper, we proposed feature-based contrast enhancement method for the digital image using 2D filter to enhance the edges and JND(Just Noticeable Difference) according to the surrounding brightness. We confirmed the result image of proposed method and identified that the contrast is improved.

• Journal of the Korea Computer Graphics Society
• /
• v.2 no.2
• /
• pp.21-28
• /
• 1996

The nature of complexity of medical images makes them difficult to segment using standard techniques. Therefore the usual approaches to segment images continue to predominantly involve manual interaction. But it tediously consumes a good deal of time and efforts of the experts. Hereby a nonmanual parameters estimation which can replace the manual interaction is needed to solve the problem of redundant manual works for an image segmentation. This paper attempts to estimate parameters for an image region segmentation using Scale Space Filtering. This attempt results in estimating the number of regions, their boundary and each representatives to be segmented 2-dimensionally and 3-dimensionally. Using this algorithm, we may diminish the problem of wasted time and efforts for finding prerequisite segmentation parameters, and lead the relatively reasonable result of region segmentation.

• Geophysics and Geophysical Exploration
• /
• v.25 no.4
• /
• pp.203-213
• /
• 2022

To understand an underlying geological structure via seismic imaging, the velocity information of the subsurface medium is crucial. Although the full-waveform inversion (FWI) method is considered useful for estimating subsurface velocity models, 3D FWI needs a lot-of computing power and time. Herein, we compare the calculation efficiency and accuracy of frequency-domain 2D and 3D acoustic FWIs. Thereafter, we demonstrate that the artifacts from 2D approximation can be partially suppressed via frequency-domain 2D FWI by employing diffraction angle filtering (DAF). By applying DAF, which employs only big reflection angle components, the impact of noise and out-of-plane reflections can be reduced. Additionally, it is anticipated that the DAF can create long-wavelength velocity structures for 3D FWI and migration.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.3
• /
• pp.55-59
• /
• 1984

This paper describes a method of Hangout recognition using 2 - D digital filtering. The 170 patterns classified by the positions of the initial sound (consonant), middle sound (vowel) and terminal sound (consonant) of the 1,659 characters were established and models formed by using 2 - D digital filtering for each patterns were obtained. Based on these models we proposed an algorithm that can recognize KOREAN combinational characters by separating patterns from them with superpostion principles. As a result of simulation, 100% of recognition rate is obtained in the case of the print letter.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2003.11a
• /
• pp.334-337
• /
• 2003

입체음향을 구현하는 방법에는 5 혹은 6 개의 스피커를 사용하는 5.1 채널 음향재생 시스템과 2개의 스피커를 사용하는 방법있다. 2 채널 입체음향재생 시스템은 라우드 스피커 재생보다 헤드폰 재생에 사용되고 있다. 2 채널로 입체음향을 재생하기 위하여 사람의 머리와 귀바퀴를 FIR 필터로 모델링한 머리전달함수(HRTF, head related transfer function)을 이용한다. FIR 필터로 측정된 HRTF는 실시간 처리에 있어서 계산량이 많은 단점이 있다. 본 논문에서는 2 채널 입체 음향시스템을 효과적으로 구현하기 위하여 FIR HRTF를 HR필터로 구현하는 방법을 제안한다. FIR 필터계수로부터 IIR 필터계수를 구하는 알고리즘은 균형화 모델 감소법(balanced model reduction)을 이용한다. 본 논문에서는 IIR 필터로 차수를 줄인 HRTF로 입체음향을 재생하는 시뮬레이션을 하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.39 no.6
• /
• pp.59-68
• /
• 2002

In this paper, we design the two-dimensional Discrete Wavelet Transform (2D DWT) filter that is widely used in various applications such as image compression because it has no blocking effects and relatively high compression rate. The filter that we used here is two-channel four-taps QMF(Quadrature Mirror Filter) Lattice filter with PR (Perfect Reconstruction) property. The proposed DWT architecture, with two consecutive inputs shows an efficient performance with a minimum of such hardware resources as multipliers, adders, and registers due to a simple scheduling. The proposed architecture was verified by the RTL simulation, and utilizes the hardware 100%. Our architecture shows a relatively high performance with a minimum hardware when compared with other approaches. An efficient memory mapping and address generation techniques are introduced and the fixed-point arithmetic analysis for minimizing the PSNR degradation due to quantization is discussed.