• IEIE Transactions on Smart Processing and Computing
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• 제3권1호
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• pp.10-18
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• 2014

From the perspective of reducing the sampling cost of color images at high resolution, block-based compressive sensing (CS) has attracted considerable attention as a promising alternative to conventional Nyquist/Shannon sampling. On the other hand, for storing/transmitting applications, CS requires a very efficient way of representing the measurement data in terms of data volume. This paper addresses this problem by developing a measurement-coding method with the proposed customized Huffman coding. In addition, by noting the difference in visual importance between the luma and chroma channels, this paper proposes measurement coding in YCbCr space rather than in conventional RGB color space for better rate allocation. Furthermore, as the proper use of the image property in pursuing smoothness improves the CS recovery, this paper proposes the integration of a low pass filter to the CS recovery of color images, which is the block-based ${\ell}_{20}$-norm minimization. The proposed coding scheme shows considerable gain compared to conventional measurement coding.

• 한국컴퓨터정보학회논문지
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• 제7권4호
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• pp.102-107
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• 2002

블록 코딩을 기반으로 하는 영상의 압축 부호화는 영상 및 비디오 압축 표준으로 적용되어 왔다. 그런데 영상 복원 시 발생하는 블록효과에 대한 효율적인 측정방법을 찾아보기 힘든 실정이다. 본 논문에서는 서브블록 DCT부호화를 이용한 복원 영상에 대한 객관적인 블록효과 측정방법을 제안한다. 제안한 방법이 주관적인 순위매김과 일치하는 블록효과 측정방법임을 실험결과로서 입증한다 또한 제안한 이 새로운 측정방법은 복원 영상에서 쉽게 그리고 효율적으로 블록효과를 측정하는데 널리 사용될 수 있을 것으로 기대한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.242-259
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• 2015

Three-dimensional video coding is one of the main challenges restricting the widespread applications of 3D video and free viewpoint video. In this paper, a novel fractal coding algorithm with motion-vector-field-based motion estimation for depth map sequence is proposed. We firstly add pre-search restriction to rule the improper domain blocks out of the matching search process so that the number of blocks involved in the search process can be restricted to a smaller size. Some improvements for motion estimation including initial search point prediction, threshold transition condition and early termination condition are made based on the feature of fractal coding. The motion-vector-field-based adaptive hexagon search algorithm on the basis of center-biased distribution characteristics of depth motion vector is proposed to accelerate the search. Experimental results show that the proposed algorithm can reach optimum levels of quality and save the coding time. The PSNR of synthesized view is increased by 0.56 dB with 36.97% bit rate decrease on average compared with H.264 Full Search. And the depth encoding time is saved by up to 66.47%. Moreover, the proposed fractal depth map sequence codec outperforms the recent alternative codecs by improving the H.264/AVC, especially in much bitrate saving and encoding time reduction.

• Journal of Information Processing Systems
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• 제19권2호
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• pp.232-239
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• 2023

Aiming at the poor compression quality of traditional image compression coding (ICC) algorithm, a multi-description ICC algorithm based on depth learning is put forward in this study. In this study, first an image compression algorithm was designed based on multi-description coding theory. Image compression samples were collected, and the measurement matrix was calculated. Then, it processed the multi-description ICC sample set by using the convolutional self-coding neural system in depth learning. Compressing the wavelet coefficients after coding and synthesizing the multi-description image band sparse matrix obtained the multi-description ICC sequence. Averaging the multi-description image coding data in accordance with the effective single point's position could finally realize the compression coding of multi-description images. According to experimental results, the designed algorithm consumes less time for image compression, and exhibits better image compression quality and better image reconstruction effect.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.607-610
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• 1998

The major objectives of speech coding include high compression ratio for transmission in the band limited channel, high synthesized speech quality in terms of the intelligibility and the naturalness and fast processing speed. In general, speech coding methods are classified into the following three categories: the wavelform coding, the source coding and the hybird coding. In this paper, we proposed a new waveform coding method using PSOLA(pitch-synchronous overlap add) technique. First, we fixed one basic waveform per pitch and measured the formant similarity between basic and neighbor waveform. Second, if the similairy satisfied threshold values, we compress the neighbor waveform per pitch and then store or transmit. When the comparession is about 45%, we obtained about 4 in MOS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1684-1699
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• 2017

The deblocking filter (DF) reduces blocking artifacts in encoded video sequences, and thereby significantly improves the subjective and objective quality of videos. Statistics show that the DF accounts for 5-18% of the total decoding time in high-efficiency video coding. Therefore, speeding up the DF will improve codec performance, especially for the decoder. In view of the rapid development of multicore technology, we propose a parallel DF scheme based on a modified order of accessing the coding tree units (CTUs) by analyzing the data dependencies between adjacent CTUs. This enables the DF to run in parallel, providing accelerated performance and more flexibility in the degree of parallelism, as well as finer parallel granularity. We additionally solve the problems of variable privatization and thread synchronization in the parallelization of the DF. Finally, the DF module is parallelized based on the HM16.1 reference software using OpenMP technology. The acceleration performance is experimentally tested under various numbers of cores, and the results show that the proposed scheme is very effective at speeding up the DF.

• 인터넷정보학회논문지
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• 제3권4호
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• pp.61-69
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• 2002

객체지향 프로그램에 대한 복잡도 측정에 관한 방법으로서 기존의 객체지향 패러다임 특성이라 할 수 있는 객체, 메시지, 클래스, 캡슐화 및 상속성 등에 관한 연구는 이미 보고된바 있다. 본 연구에서는 측정인자로서 Halstead의 Program Volume, Program Level, Program Impurity, Macabe의 Cyclomatic Number, Handerson-Sellers의 응집도 결핍척도 Sullivan's의 PVG측정 방법 등을 선택하였다. 시뮬레이션으로는 객체지향 프로그램의 대표적인 언어인 JAVA Program을 Design & Coding할 때 도움을 주는 척도에 대해서 JAVA Sample Program을 준비하여 프로그램 복잡도 면에서 측정인자들을 각각 비교·분석하였다.

• 한국콘텐츠학회논문지
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• 제19권3호
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• pp.80-88
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• 2019

사용자와 감성적인 소통(Emotional Communication)이 중요한 제품 디자인 영역에서 디자이너가 사용자 감성을 보다 명확하고 신속하게 파악하는 것은 제품 디자인 연구의 매우 핵심적인 활동이다. 이에 본 연구는 제품디자인과정에 감성측정의 활용가능성을 높이기 위한 방법으로서 행위적 감성 측정 방법인 표정 부호화 시스템(Facial Action Coding System, FACS)을 제품디자인 평가에 활용하였다. 표본으로 선정한 감성 제품의 Image Map을 활용하여 긍정적, 부정적, 중성 감성을 유발하는 제품 자극물 총 6개를 선정하여 20대 일반 제품 사용자를 실험 대상으로 FACS 실험을 진행하고 사용자 얼굴 표정을 통하여 자극물에 대한 감성상태를 분석하였다. 이러한 실험을 통하여 표정 부호화 시스템이 제품디자인에 적용 과정에서 "사용자 무의식적인 얼굴 표정을 기록할 수 있다" 등 장단점을 분석하였으며 "사용자 반응도 높은 제품 자극물을 선정해야 한다" 등 적용방안을 제시하였다. 본 연구는 향후 새로운 제품을 시장에 출시하기 전에 제품디자인 시안 단계에서 사전 사용자 감성 예측 방법으로 FACS를 활용성 검토에 도움을 줄 것으로 전망된다.

• 기술사
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• 제22권2호
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• pp.19-25
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• 1989

Utilizing a cosine transform in image compression has several recognized performance benefits, resulting in the ability to attain large compression ratio with small quality loss. Also, various models incorporating Human Visual System (HVS) to Discrete Cosine Trans-form (DCT) scheme are considered. Using the exact frequency components of DCT basis function, the optimum modulation transfer function (MTF) is obtained analytically. The errors at a block boundary which is important factor in transform coder are criteria for error measurement. The HVS weight coding results in perceptually higher quality images compared with the unweighted scheme.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권7호
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• pp.434-441
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• 2003

This paper proposes a new quantitative and objective image quality metric which is essential to verify the performance of block-based DCT image coding. The proposed metric considers not only global distortion of coded image such as spatial frequency sensitivity and channel masking using HVS based multi-channel model, but also structural distortions caused block-based coding. The experimental results show a strong correlation between proposed metric and subjective metric.