• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.631-633
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• 2022

인체 선형 모델 (이하 SMPL 모델)은 3 차원 사람 모델로, 3 차원 컴퓨터 그래픽 기술이 발전함에 따라 활용 범위가 확대될 수 있다. 다운샘플링 (Down-sampling)으로 여러 해상도의 SMPL 모델이 사용가능 하다면, 3 차원 컴퓨터 그래픽 기술 발전에 도움이 될 것이다. 3 차원 모델의 다운샘플링을 위한 많은 메쉬 단순화 (Mesh simplification) 기법이 존재한다. 하지만 기존의 기법만을 사용하면 다운 샘플링 한 모델의 자세 (Pose)를 변경했을 때 기대한 것과 다른 결과물이 만들어지는 문제가 발생한다. 본 논문에서는 가장 가까운 정점으로 SMPL 모델의 관절 회귀자 (Joint regressor) 값을 넘겨주어 문제를 해결하는 다운샘플링 (Down-sampling) 방법을 제시한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.235-236
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• 2019

본 논문에서는 초해상도, 압축 열화 제거 등 영상 화질 복원 연구에서 영상의 다운샘플링에 딥러닝을 적용한 연구들에 대해 소개한다. 첫 번째 연구는 두 개의 컨볼루셔널 신경망과 영상 압축 코덱을 이용하여 압축 영상의 화질을 향상시켰다. 두 번째 연구는 초해상도 문제를 해결함에 있어 다운샘플링 역시 딥러닝을 통해 학습하여 복원 영상의 화질을 향상시켰다. 두 연구를 통해 영상 화질 개선 문제 해결에 있어 적절한 딥러닝 학습 방법을 영상 다운샘플링에 적용하여 좋은 결과를 얻을 수 있다는 것을 확인할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.11
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• pp.918-926
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• 2012

In 3D video transmission, a depth map being used for depth image based rendering (DIBR) is generally compressed by reducing resolution for coding efficiency. Errors in resolution reduction are recovered by an appropriate up-sampling method after decoding. However, most previous works only focus on up-sampling techniques to reduce errors. In this paper, we propose a novel down-sampling technique of depth map that applies different down-sampling rates on moving objects and background in order to enhance human perceptual quality. Experimental results demonstrate that the proposed scheme provides both higher visual quality and peak signal-to-noise ratio (PSNR). Also, our method is compatible with other up-sampling techniques.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.77-79
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• 2013

본 논문에서는 광원 정보를 사용하여 다양한 재생환경에서 효과적인 홀로그래픽 비디오 서비스를 제공하기 위한 방법을 제안한다. 제안하는 기법에서 부호화 과정에서는 가우시안 블러를 적용한 영상의 개수를 조절, 분리 하고 다운 샘플링 한 하나의 영상 압축을 한 뒤 전송한다. 이 영상을 다운 샘플링, 업 샘플링, 보간법, 양방향 필터 (Bi-lateral filter) 등의 기법을 이용하여 획득한 영상과 나머지 영상을 다운 샘플링과 업 샘플링 하여 더한 영상의 차를 압축하여 수신측으로 전송한다. 복호화 과정에서는 압축된 광원 정보를 복원한 후 기본계층 정보를 가진 영상을 업 샘플링과 보간법, 양방향 필터 (Bi-lateral filter) 등의 기법을 적용하고 수신자의 환경과 고려에 따라 차영상을 더 한 후 CGH를 통해 홀로그램을 획득하였다. 실험을 통해 제안하는 기법이 기존의 방법들 보다 우수한 홀로그램을 복원 할 수 있다는 것을 확인하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.68-74
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• 2017

This paper presents a joint demosaicking and arbitrary-ratio down sampling algorithm for color filter array (CFA) images. Color demosaiking is a necessary part of image signal processing pipeline for many types of digital image recording system using single sensor. Also, such as smart phone, obtained high resolution image from image sensor has to be down-sampled to be displayed on the screen. The conventional solution is "Demosaicking first and down sampling later". However, this scheme requires a significant amount of memory and computational cost. Also, artifacts can be introduced or details get damaged during demosaicking and down sampling process. In this paper, we propose a method in which demosaicking and down sampling are working simultaneously. We use inverse mapping of Bayer CFA and then joint demosaicking and down sampling with arbitrary-ratio scheme based on signal decomposition of high and low frequency component in input data. Experimental results show that our proposed algorithm has better image quality performance and much less computational cost than those of conventional solution.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.29-30
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• 2015

본 논문에서는 음악 시디에 사용되는 44.1khz의 포맷으로 녹음된 주파수와, 고품질 녹음시 선택하는 포맷인 96khz로 녹음한 주파수를 다시 44.1khz로 다운 샘플링한 주파수를 비교 분석한다. 다양한 주파수를 다운 샘플링 한 후 변화된 주파수의 평균을 분석하여 이의 특성을 제시한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.465-469
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• 2017

In this paper we propose a human body tracking method for application of smartphones. The conventional human body tracking method is divided into a sensor-based method and a vision-based method. The sensor-based methods have a weakness in that tracking accuracy is low due to cumulative error of position information. The vision-based method has no cumulative error, but it requires reduction of the computational complexity for application of smartphone. In this paper we use the improved HOG algorithm as a human body tracking method for application of smartphone. The improved HOG algorithm is implemented through downsampling and frame sampling. Gaussian pyramid is applied for downsampling, and uniform sampling is applied for frame sampling. We measured the proposed algorithm on two devices, four resolutions, and four frame sampling intervals. We derive the best detection rate among downsampling and frame sampling parameters that can be applied in realtime.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.743-750
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• 2000

In this paper, low-power block filtering architecture for digital If down sampler and up sampler is proposed. Software radio technology requires low power and cost effective digital If down and up sampler. Digital If down sampler and up sampler are accompanied with decimation filter and interpolation filter, respectively. In the proposed down sampler architecture, it is shown that the parallel and low-speed processing architecture can be produced by cancellation of inherent up sampler of block filter and down sampler. Proposed up sampler also utilizes cancellation of up sampler and inherent down sampler of block filtering structure. The proposed architecture is compared with the conventional polyphase architecture.

• Journal of Korean Society of Forest Science
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• v.112 no.2
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• pp.195-208
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• 2023

This study aimed to use three-dimensional point cloud data (PCD) obtained from Terrestrial Laser Scanning (TLS) and Mobile Laser Scanning (MLS) to evaluate a deep learning-based species classification model for two tree species: Pinus koraiensis and Larix kaempferi. Sixteen models were constructed based on the three conditions: LiDAR platform (TLS and MLS), down-sampling intensity (1024, 2048, 4096, 8192), and deep learning model (PointNet, PointNet++). According to the classification accuracy evaluation, the highest kappa coefficients were 93.7% for TLS and 96.9% for MLS when applied to PCD data from the PointNet++ model, with down-sampling intensities of 8192 and 2048, respectively. Furthermore, PointNet++ was consistently more accurate than PointNet in all scenarios sharing the same platform and down-sampling intensity. Misclassification occurred among individuals of different species with structurally similar characteristics, among individual trees that exhibited eccentric growth due to their location on slopes or around trails, and among some individual trees in which the crown was vertically divided during tree segmentation.

• Journal of KIISE:Software and Applications
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• v.30 no.7_8
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• pp.687-695
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• 2003

In this paper, we present a document image compression system based on segmentation, Quincunx downsampling, (5/3) wavelet lifting and subband-oriented SPIHT coding. We reduced the coding time by the adaptation of subband-oriented SPIHT coding and Quincunx downsampling. And to increase compression rate further, we applied arithmetic coding to the bitstream of SPIHT coding output. Finally, we present the reconstructed images for visual comparison and also present the compression rates and PSNR values under various scalar quantization methods.