• Journal of IKEEE
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• v.2 no.1 s.2
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• pp.96-100
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• 1998

Due to expected wide spread use of DCT based image/video coding standard, it is advantageous to process data directly in the DCT domain rather than decoding the source back to the spatial domain. The block processing algorithm provides a parallel processing method since multiple input data are processed in the block filter structure. Hence a fast implementation of the algorithm is well suited. In this paper, we propose the JPEG browse by Block Transform Domain Filtering(BTDF) using subband filter banks. Instead of decompressing the entire image to retrieve at full resolution from compressed format, a user can select the level of expansion required$(2^N{\times}2^N)$. Also this approach reduces the computer cpu time by reducing the number of multiplication through BTDF in the filter banks.

• ETRI Journal
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• v.41 no.3
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• pp.316-325
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• 2019

Accurate suppressive jamming is a prominent problem faced by radar equipment. It is difficult to solve signal detection problems for extremely low signal to noise ratios using traditional signal processing methods. In this study, a joint sensing dictionary based compressed sensing and adaptive iterative optimization algorithm is proposed to counter suppressive jamming in information domain. Prior information of the linear frequency modulation (LFM) and suppressive jamming signals are fully used by constructing a joint sensing dictionary. The jamming sensing dictionary is further adaptively optimized to perfectly match actual jamming signals. Finally, through the precise reconstruction of the jamming signal, high detection precision of the original LFM signal is realized. The construction of sensing dictionary adopts the Pei type fast fractional Fourier decomposition method, which serves as an efficient basis for the LFM signal. The proposed adaptive iterative optimization algorithm can solve grid mismatch problems brought on by undetermined signals and quickly achieve higher detection precision. The simulation results clearly show the effectiveness of the method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8A
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• pp.836-845
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• 2002

Video summary is one of the tools which can provide the fast and effective browsing for a lengthy video. Video summary consists of many key-frames that could be defined differently depending on the video genre it belongs to. Consequently, the video summary constructed by the uniform manner might lead into inadequate result. Therefore, identifying the video genre is the important first step in generating the meaningful video summary. We propose a new method that can classify the genre of the video data in MPEC compressed bit-stream domain. Since the proposed method operates directly on the compressed bit-stream without decoding the frame, it has merits such as simple calculation and short processing time. In the proposed method, only the visual information is utilized through the spatial-temporal analysis to classify the video genre. Experiments are done for 6 genres of video: Cartoon, commercial, Music Video, News, Sports, and Talk Show. Experimental result shows more than 90% of accuracy in genre classification for the well -structured video data such as Talk Show and Sports.

• The Transactions of the Korea Information Processing Society
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• v.6 no.5
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• pp.1296-1302
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• 1999

In this paper, we propose an algorithms for the mounted PCB classification system using wavelet transform and ART2 neural network. The feature informations of a mounted PCB can be extracted from the coefficient matrix of wavelet transform adapted subband concept. As the preprocessing process, only the PCB area in the input image is extracted by histogram method and the feature vectors are composed of using wavelet transform method. These feature vectors are used as the input vector of ART2 neural network. In the experiment using 55 mounted PCB images, the proposed algorithm shows 100% classification rate at the vigilance parameter $\rho$=0.99. The proposed algorithm has some advantages of the feature extraction in the compressed domain and the simplification of processing steps.

• Journal of Korea Multimedia Society
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• v.11 no.12
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• pp.1668-1675
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• 2008

In this paper, we propose a post-processing technique developed for the subjective improvement of color resolution in DCT-coded color images. The high frequency components caused by complex object parts are compressed and impaired through DCT-based image processing, so color distortions such as blurs in high saturated regions are observed. It's mainly due to the severe loss of color data as Cb and Cr. Generally, the activities of chroma elements in DCT domain correlate strongly with that of luminance as spatial frequency gets higher, and based on the relations between chroma and luma AC activities, we compensate destructed Cb, Cr coefficients using modifications from Y coefficients. Simulation results show that the proposed method enhances color resolution in high saturated region, and improves the visual quality.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.1
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• pp.56-63
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• 2009

Nowdays, Most of Internet Contents delivered as a compressed file. It gives many advantages like deduction of communication bandwidth and transmission time etc. In case of JPEG Compression, Quantization is the most important procedure which accomplish the compression. In general signal processing, Quantization is the process which converts continuous analog signal to discrete digital signal. As you known already, Quantization over JPEG compression is to reduce magnitude of pixel value in spatial domain or coefficient in frequency domain. A lot of Data Hiding algorithms also developed to applicable for those compressed files. In this paper, we are going to unveil the influence of quantization table which used in the process of JPEG compression. Even thought most of algorithm modify frequency coefficients with considering image quality, they are ignoring the influence of quantization factor corresponding with the modified frequency coefficient. If existing algorithm adapt this result, they can easily evaluate their performances.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1141-1144
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• 2011

Range walk has been a major problem in achieving correct Doppler processing. This frequently occurs when range variation is severe just like in a bistatic radar or in high speed target scenario. This paper presents a range walk compensated range-Doppler processing algorithm applicable to the bistatic radar. In order for the compensation, a range-domain interpolation is applied for range compressed signal so that Doppler processing is performed along the evenly time-spaced range bins that contain target returns. Under a bistatic radar scenario, the proposed algorithm including a range domain pulse compression is mathematically described. Finally, the validity of the algorithm is demonstrated by simulation results showing the superiority of a SCDP(Squint Cross-range Doppler Processing) over an uncompensated Doppler processing.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.139-142
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• 2002

본 논문은 이 기종간의 표준 압축형식을 변환하는데 있어 실시간 변환이 가능하도록 하며 프레임의 특성을 이용하여 압축률을 좀 더 높여 보는데 그 목적을 두고 있다. 이 기종간의 표준 압축형식 변환으로 MPEG2에서 H.263으로의 변환을 시도하였다. MPEG2에서 H.263으로 변환 시 압축률을 높이기 위한 분석결과 MPEG2 의 P 프레임내 인트라 매크로블록이 H.263 의 P 프레임의 인트라 매크로블록 수보다 많다는 것을 알 수 있었다. 따라서 본 논문에서는 P 프레임의 압축률을 높이기 위하여 P 프레임내의 인트라 매크로블륵 변환 과정에 움직임 예측과정을 삽입하고 움직임 예측 과정의 복잡도를 줄이기 위하여 Guided 탐색 방법을 사용하여 MPEG2 P 프레임에 생성된 인트라 매크로블록의 개수를 줄일 수 있다는 것을 제안하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.151-154
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• 2002

모바일 환경등의 저대역 통신망에서 VOD 서비스를 제공하기 위해서는 영상 데이터의 크기를 줄이는 방법이 요구된다. 데이터를 줄이는 방법 중 가장 효율적인 방법이 영상 크기 축소 트랜스코더 (Resolution Downscale Transcoder)이지만 시스템의 리소스를 많이 소모하게 되므로 이를 줄이는 방법으로 움직임 예측을 최소화하는 움직임 벡터 병합 방법이 연구되었다. 하지만 이러한 방법들은 보다 정확히 움직임 벡터를 생성하지만 실제 영상에는 크게 적용되지 못하고 있다. 따라서 본 논문에서는 움직임벡터를 병합하는 비율을 높여 움직임 예측을 줄이고 인트라 영역에서의 변환 과정을 간소화하여 전체적인 시스템 리소스의 소모를 줄이도록 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.7-10
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• 2002

본 논문에서는 MPEG-7의 활동도 기술자를 이용한 비디오 기술을 제안한다. 제안한 방법은 압축상태의 비디오 자료에서 직접 움직임 벡터들을 추출, 각 프레임들의 활동도의 강도를 계산하고 프레임의 흐름에 따라 계산된 활동도의 변화량에 대해 퓨리에 변환을 적용하여 얻어진 주파수 성분을 분석하여 활동도의 시간적 분포도를 계산한다. 계산된 강도 및 분포도는 MPEG-7의 표준에 따르기 위해 양자화하여 비디오 요약에 이용한다.