• 전자공학회논문지B
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• 제30B권10호
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• pp.1-12
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• 1993

A multiprocessor system for high-speed processing of hybrid image coding algorithms such as H.261, MPEG, or Digital HDTV is presented in this study. Using a combination of highly parallel 32-bit microprocessor, DCT(Discrete Cosine Transform), and motion detection processor, a new processing module is designed for the implementation of high performance coding system. The sysyem is implemented to allow parallel processing since a single module alone cannot perform hybrid coding algorithms at high speed, and crossbar switch is used to realize various parallel processing architectures by altering interconnections between processing modules within the system.

• ETRI Journal
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• 제33권4호
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• pp.641-644
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• 2011

In this letter, we propose a novel bitrate control, using both Kalman and FIR filters, based on a Hamiltonian analysis with respect to the amount of bits from each macroblock, in an encoding of a general video codec such as H.264/AVC. Since the proposed bitrate control is based on the simple computation of an optimal control method based on the Hamiltonian analysis, it is not necessary to use additional computation, such as a DCT or quantization, to estimate the bits for bitrate control. As a result, the proposed algorithm can be applied to single-pass encoding and can provide sufficient encoding speed with respect to various applications, even those requiring real-time control.

• 한국통신학회논문지
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• 제31권4C호
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• pp.458-471
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• 2006

Digital watermarking of multimedia data is a very active research area that has enjoyed a considerable amount of attention in recent years. In this paper, we propose an algorithm for embedding/detecting a fragile watermark in MPEG-4 compressed video domain (Simple and Advance Simple Profiles). The watermark bits are put directly into Huffman VLC-codespace of quantized DCT domain. The advantage of watermark embedding into the compressed domain is the significant savings for a real-time implementation as it does not require a full decoding operation. The watermark embedding does not change the video file size. The algorithm demonstrates high watermarking capacity, thereby providing reliable foolproof authentication. The results of experimental testing demonstrate that watermark embedding preserves the video quality. Watermark detection is performed without using the original video.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.36-42
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• 1997

This paper presents a new design technique for performing high quality low bit rate image compression. A hybrid coder(HC) which combines Mean Removed Important Coefficient Selection based JPEG(MR-ICS-JPEG) and Adaptive Vector Quantization (AVQ) is proposed. A new quantization table is developed using the Important Coefficient Selection(ICS) method; the importance of each coefficient is determined using the orthonormal property of the DCT. This quantization table is applied to standard JPEG with mean removal(MR) strategy before processing. This scheme, called MR-ICS-JPEG, produces more than 2 dB enhanced performance in terms of PSNR over standard JPEG. A set of homogeneous codebooks is generated by homogeneous training vectors. Before compression, an image is uniformly divided into 8${\times}$8 blocks. Low detail regions such as backgrounds are roughly coded by AVQ while high detail regions such as edges or curves are finely coded by the proposed MR-ICS-JPEG. This hybrid coder procuces consistently about 3 dB improved performance in terms of PSNR over standard JPEG.

• 한국산업정보학회논문지
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• 제14권3호
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• pp.37-43
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• 2009

스테가노그래피는 인터넷에서 은닉메시지가 보내어지는 사실 자체를 숨기는 것이다. 일반적인 스테간 분석은 스테고 신호의 통계량에서 갑작스런 변화인 이상치를 감지하는 것이다. 혼합된 스테고 이미지에 비해 은닉자료가 매우 작은 경우 은닉된 자료의 감지와 위치를 찾아내는 일반적이고 효과적인 감지기법 즉, 이웃한 4개의 픽셀값을 이용한 삽입용량값과 카이스퀘어 검사기법 등을 함께 고려하는 개선된 방법을 제시한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.451-454
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• 2004

The reconfigurable architecture is increasingly important for design of multi-mode communication systems and computation-intensive DSP systems. The proposed coarse-grain architecture is based on a reconfigurable processing element consisting of a MAC unit, a register file, a context data register, and PE interconnect control blocks. The main feature of the Proposed architecture is the loop context which enables faster configuration. Also, we propose another area-efficient reconfigurable architecture with improved reconfigurability. The SystemC modeling results show that the proposed architecture can reduce 9 clock cycles of 2D DCT compared to existing architectures.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.553-556
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• 2000

This paper proposes an adaptive linearization method of Volterra nonlinear systems using DWT(Discrete Wavelet Transform)and an LMS-type predistorter. In particular, the proposed wavelet transform-domain lineatization method leads to diagonalization of the input vector auto-correlation matrix which yields improvement of the convergence rate of the corresponding transform-domain LMS algorithm. Furthermore, the adaptive Volterra predistorter followed by a corresponding weakly Volterra nonlinear system(here. a TWT amplifier model in a satellite communication system) is utilized to compensate for the distortion in the output. Also,12-PSK and 4-QAM are applied as the input to the nonlinear system to be tested. Some simulation results show that the proposed linearization approach has better performance than DCT-based or conventional normalized LMS algorithms do.

• 응용통계연구
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• 제24권1호
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• pp.35-43
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• 2011

이 논문에서는 이산코사인변환(discrete cosine transform) 계수를 이용하여 AR(1) 과정에서 단위근을 검정하는 방법을 소개한다. 제안하고자 하는 방법의 이론적 타당성을 보이기 위해 정상 AR(1) 과정과 확률보행과정 하에서의 이산코사인변환 계수의 통계적 성질을 비교한다. 비교 결과를 이용하여 단위근 여부를 확인할 수 있는 검정통계량을 제안하고 붓스트랩을 활용하여 검정통계량의 분포를 유도한다. 모의실험을 통해 기존 Dickey-Fuller 검정과 검정력 비교를 실시하였다.

• 한국정보처리학회논문지
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• 제7권7호
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• pp.2254-2263
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• 2000

This paper proposes an efficient predictive image-compression technique based on vector quantization of blocks of pels. In the proposed method edge contents of blocks control the selection of predictors and block shapes as well. The maximum number of bits assigned to quantizers has been in creased to 3bits/pel from 1/5bits/pel, the setting employed by forerunners in predictive vector quantization of images. This increase prevents the saturation in SNR observed in their results in high bit rates. The variable block shape is instrumental in eh reconstruction of edges. The adaptive procedure is controlled by means of he standard deviation ofp rediction errors generated by a default predictor; the standard deviation address a decision table which can be set up beforehand. eh proposed method is characterized by overall improvements in image quality over A-VQ-PE and A-DCT VQ, both of which are known for their efficient use of vector quantizers.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.577-580
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• 1999

Padding is a technique that enables applying conventional discrete cosine transform to encode boundary blocks of arbitrarily shaped objects by assigning imaginary values to the pixels that are not included in the object. Padding prevents the increase of high frequency DCT coefficients. However, in some boundary blocks, too many padded pixels are coded due to a small portion of object pixels. To reduce the number of padded pixels and to improve coding efficiency, we propose a block merging method for texture coding. The proposed mothed searches the shape information of boundary blocks and excludes the 4$\times$4 pixels of 8$\times$8 blocks if all the 4$\times$4 pixels are in the background region, and merges the remained 4$\times$4 pixels into new 8$\times$8 blocks. Experimental results show that our proposed method yields a rate-distortion gain about 0.5~1.6㏈ compared to conventional padding method, LPE