• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.4
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• pp.766-772
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• 2007

H.264/AVC is a new international standard for the compression of video images, in which a deblocking filter has been adopted to remove blocking artifacts. This paper proposes an efficient architecture of deblocking filter in H.264/AVC. By making good use of data dependence between neighboring $4{\times}4$ blocks, the memory size is reduced and the throughput of the deblocking filter processing is increased. Compared to the conventional deblocking filters, the proposed architecture enhances the performance of deblocking filter processing from 1.75 to 4.23 times. Hence the proposed architecture is able to perform real-time deblocking of high-resolution($2048{\times}1024$) video applications.

• Journal of IKEEE
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• v.23 no.3
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• pp.925-933
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• 2019

In this paper, we implement ZYNQ SoC-based post-processing system that utilizes partial reconfiguration to remove blocking artifacts generated by compression algorithm. Hardware implementation of the deblocking filter in a Field Programmable Gate Array (FPGA) provides high computational capability and can be partially reconfigured to process 1080p images in real time. Partially reconfigurable areas in FPGA can be utilized to use hardware more efficiently in highly resource-constrained embedded systems. Experimental results of the proposed system show improvement of visual quality both objectively and subjectively with 0.6dB higher PSNR after deblocking filtering process. The measured power consumption of the deblocking filter during run-time is 68.33mW.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.403-406
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• 2000

본 논문에서는 저비트율 영상통신에서 발생되는 블록화현상과 컬러 번짐 현상을 효과적으로 줄임으로써, 주관적 화질을 개선하는 후처리 필터를 제안한다. 저비트율 영상통신에서 8*8 블록 단위의 DCT 수행은 블록화 및 컬러 번짐 현상과 같은 화질 열화를 초래한다. 이러한 화질 열화를 개선하기 위하여 밝기 영역과 컬러 영역에서 각기 다른 후처리 필터를 본 논문에서 제안한다. 밝기 부분의 후처리 필터에서는 일률적인 후처리 필터에서 발생하게 되는 새로운 artifact 인 geometric pattern 을 방지하기 위해 각 화소의 공간영역에서 블록 경계 좌우로 filtering range 를 다르게 수행하고, 컬러부분의 후처리 필터에서는 컬러번짐 현상을 최대한 억제하기 위해 블록간 컬러 값의 차이에 따라 다르게 수행되는 후처리 필터를 제안한다. 제안된 실험을 통하여 후처리 필터를 수행한 영상화질이 H.263 baseline 에 비해 월등히 나아짐을 확인할 수 있었으며, H.263 Annex J의 deblocking filter mode에 비해서도 떨어지지 않는 화질을 얻을 수 있었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.264-267
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• 2014

본 논문에서는 High Efficiency Video Coding (HEVC)의 확장 버전에 적용된 바 있는 화면 내 블록 복사 (Intra Block Copy; IntraBC) 기술에 대해 개선 알고리듬을 제안하고 있다. IntraBC 는 화면 내 부호화 진행 시, 예측 유닛 (prediction unit; PU)단위로 현재 부호화하고 있는 코딩 트리 유닛 (coding tree unit; CTU)의 왼쪽에 위치하는 CTU 를 탐색하는 기법이다. 이때, 왼쪽 CTU 에서 가장 비슷한 블록을 찾아 그 움직임 벡터 (motion vector)를 저장 및 전송하게 된다. 제안하는 알고리듬은 움직임 벡터를 찾기 전, 왼쪽의 복원된 CTU 에 대해 특정 필터를 적용하여 블록킹 열화 (blocking artifact)를 완화시키고, 더욱 정확하고 섬세한 움직임 벡터를 찾도록 하였고, 이는 자연영상보다 스크린 콘텐츠에 더욱 적합함을 확인할 수 있었다.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.306-307
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• 2008

본 논문에서는 제한적인 자원이 할당된 모바일 환경에서 블록기반의 압축방식을 사용하여 영상을 복원할 때에 나타나는 블록화 연상을 제거하기 위해 효율적인 실시간 후처리 기법을 제안한다. 제안하는 후처리 기법은 영상에 존재하는 블록화 현상으로 인해 나타나는 다양한 인공물에 대해 디블록킹 필터링와 방향성 필터링를 적용하여 효율적으로 블록화 현상을 제거한다. 후처리 과정 중 영상에 존재하는 고유의 고주파 성분과 인공물로 인한 고주파 성분을 구분하여, 필더링 과정으로 고유의 고주파 성분이 함께 제거되지 않도록 보호해준다. 다양한 영상을 통해 본 논문에서 제안한 후처리 기법과 기존에 알려진 후처리 기법들을 비교하는 실험을 하였고, 도출된 실험 결과를 객관적인 지표로 제시하여 제안하는 기법의 우수함을 입증하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.27-30
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• 2006

본 논문은 디지털 모바일 비디오에 대한 객관적 화질 평가 방법을 제안한다. 본 논문에서 제시하는 화질 평가 방법은 경계 영역을 구한 뒤, 그 주변 영역에서의 에러 값에 근거한 경계영역 특징과 영상 압축 코덱에 의하여 발생하는 블로킹 효과를 측정함으로써 주관적 화질을 객관화 하였다. 제안한 알고리듬의 성능 평가를 위하여 Mean Opinion Score (MOS)값과 기존의 방법/제안한 방법의 결과를 비교하였다. 본 논문에서는, 인간 시각에 의한 MOS값과의 상관도가 제안한 방법이 기존의 방법에 비하여 비교적 큼을 보였다.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.73-85
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• 1998

The purpose of this study was to aid in the use of the digital images by edge-detect interpolation for direct digital periapical images using edge-detect interpolation. This study was performed by image processing of 20 digital periapical images; pixel replication, linear non-interpolation, linear interpolation. and edge-sensitive interpolation. The obtained results were as follows : 1. Pixel replication showed blocking artifact and serious image distortion. 2. Linear interpolation showed smoothing effect on the edge. 3. Edge-sensitive interpolation overcame the smoothing effect on the edge and showed better image.

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.177-183
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• 1993

Medical imagies with high resolution are coded to be archived and communicated in MPACS. In this paper, we have studied on coding of Cardio-Angiography. Our coding technique is Subband-Vector Quantization. This techniques is irreversible coding method. This technique's advantages are removing blocking artifact and edge degradation, adapting for drastic image change because of dye injection, and fast decoding. We achieved good results for Cardio-Angiography data, but the study on more sophiscated motion estimation techniques and VQ techniques must be performed.

• Journal of Korea Multimedia Society
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• v.25 no.1
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• pp.29-38
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• 2022

Although image compression is one of the essential technologies to transmit image data on a variety of surveillance and mobile healthcare applications, it causes unnecessary compression artifacts such as blocking and ringing artifacts by the lossy compression in the limited network bandwidth. Recently, image restoration methods using convolutional neural network (CNN) show the significant improvement of image quality from the compressed images. In this paper, we propose Image Denoising Convolutional Neural Networks (IDCNN) to reduce the compression artifacts for the purpose of improving the performance of object classification. In order to evaluate the classification accuracy, we used the ImageNet test dataset consisting of 50,000 natural images and measured the classification performance in terms of Top-1 and Top-5 accuracy. Experimental results show that the proposed IDCNN can improve Top-1 and Top-5 accuracy as high as 2.46% and 2.42%, respectively.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.335-341
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• 2018

With the improvement of medical state, patients' expectations for the most advanced medical equipment are increasing. Particularly, Magnetic Resonance Image (MRI) is used as one of the core image diagnosis methods in all clinical area. However, it has been reported that many of patients who go through the examination suffer from anxiety to the severe noise level during the examination. In this study, both the noise reduction evaluation of headsets with sound-blocking materials added to existing sound-absorbing materials and the existence of sound blocking materials as artifacts on the examination image are tested. An MRI test noise is recorded as a speaker by cross-ordination the sound material (sponge) and the sound material (acrylic plate, copper plate, and 3D copper plate) inside the headset made from 3D pring. A quantitative assessment of headsets showed that the average headset value was 81.8 dB. The average dB value of the most soundproof material combination(Copper, acrylic plate, sponge, sponge) headsets on headsets with added charactering material was measured at 70.4 dB, and MRI showed that the copper was diamagnetic substance and excluded. The second most soundproof headset(Sponge, acrylic plate, 3D copper plate, sponge) was measured at 70.6 dB and MRI showed no artifacts. The same simulation of the material printed with a 3D copper PLA containing approximately 40 % copper powder resulted in no artifacts, therefore, the material output as a 3D printing was better suited for use. For MRI related research, the mutual development of 3D printing is highly anticipated.