• The KIPS Transactions:PartB
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• v.12B no.6 s.102
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• pp.637-646
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• 2005

Most of the multimedia contents for DBM services art provided as MPEG-2 bit streams. However, they have to be transcoded to H.264 bit streams for practical services because the standard video codec for DMB is H.264. The existing transcoder architecture is Cascaded Pixel-Domain Transcoding Architecture, which consists of the MPEG-2 dacoding phase and the H.264 encoding phase. This architecture can be easily implemented using MPEG-2 decoder and H.264 encoder without source modifying. However. It has disadvantages in transcoding time and DCT-mismatch problem. In this paper, we propose two kinds of transcoder architecture, DCT-OPEN and DCT-CLOSED, to complement the CPDT architecture. Although DCT-OPEN has lower PSNR than CPDT due to drift problem, it is efficient for real-time transcoding. On the contrary, the DCT-CLOSED architecture has the advantage of PSNR over CPDT at the cost of transcoding time.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.585-590
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• 2002

In the typical data partitioning for error-resilient video coding, motion and macroblock header information is separated from the texture information. It can be an effective tool for the transmission of video over the error prone environment. For Intra-coded frames, however, the loss of DCT (discrete cosine transform) coefficients is fatal because there is no ther information to reconstruct the corrupted macroblocks by errors. For Inter-coded frames, when error occurs in DCT coefficients, the picture quality is degraded because all DCT coefficients are discarded in those packets. In this paper, we propose an efficient data partitioning and coding method for DCT-based error-resilient video. The quantized DCT coefficients are partitioned into the even-value approximation and the remainder parts. It is shown that the proposed algorithm provides a better quality of the high priority part than the conventional methods.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.9
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• pp.22-32
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• 1997

This paper proposes an imprecise compuitation model for DCT considering QOS of images and a two dimensional DCT architecture for imprecise computations. In case that many processes are scheduling in a hard real time system, the system resources are shared among them. Thus all processes can not be allocated enough system resources (such as processing power and communication bandwidth). The imprecise computtion model can be used to provide scheduling flexibility and various QOS(quality of service)levels, to enhance fault tolerance, and to ensure service continuity in rela time systems. The DCT(discrete cosine transform) is known as one of popular image data compression techniques and adopted in JPEG and MPEG algorithms since the DCT can remove the spatial redundancy of 2-D image data efficiently. Even though many commercial data compression VLSI chips include the DCST hardware, the DCT computation is still a very time-consuming process and a lot of hardware resources are required for the DCT implementation. In this paper the DCT procedure is re-analyzed to fit to imprecise computation model. The test image is simulated on teh base of this model, and the computation time and the quality of restored image are studied. The row-column algorithm is used ot fit the proposed imprecise computation DCT which supports pipeline operatiions by pixel unit, various QOS levels and low speed stroage devices. The architecture has reduced I/O bandwidth which could make its implementation feasible in VLSI. The architecture is proved using a VHDL simulator in architecture level.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.157-160
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• 2003

In this paper. we propose a simple and effective video scene change detection algorithm using a 3-D DCT. The 3-D DCT that we employ is a 2$\times$2$\times$2 DCT has simple computations composed only of adding and shifting operations. The simple average values of multiresolution represented video using the 2$\times$2$\times$2 DCT are used as a detection feature vector.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.2
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• pp.106-112
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• 2007

This paper proposes a hybrid architecture algorithm for fast computation of DCT and DFT via recursive factorization. Recursive factorization of DCT-II and DFT transform matrix leads to a similar architectural structure so that common architectural base may be used by simply adding a switching device. Linking between two transforms was derived based on matrix recursion formula. Hybrid acrchitectural design for DCT and DFT matrix decomposition were derived using the generation matrix and the trigonometric identities and relations. Data flow diagram for high-speed architecture of Cooley-Tukey type was drawn to accommodate DCT/DFT hybrid architecture. From this data flow diagram computational complexity is comparable to that of the fast DCT algorithms for moderate size of N. Further investigation is needed for multi-mode operation use of FFT architecture in other orthogonal transform computation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.3
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• pp.239-253
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• 1987

By the extension and the modification of the efficient aigorithms for the DCT-III, the fast algorithms to compute three versions for DCT, four versions of DST, and a DHT are developed. It is shown that the algorithms developed in this paper have simple structures and the numbers of multipication and addition are reduced as comparies with the existing efficient algorithms. The algorithms presentes in this paper indicate the close relationship amng different versions of the DCT and DST as well as a DHT. The formulas to compute the numbers of multiplication and addition of them are derived.

• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1163-1170
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• 2013

Digital watermarking techniques have been used as one of the means for copyright protection and authentication of multimedia data. Conventional Chinese Remainder Theorem(CRT)-based spatial domain watermarking techniques do not perform well under JPEG compression. However, it is seen that the CRT-based watermarking technique in Discrete Cosine Transform(DCT) domain performs well for JPEG compression. In this paper, an improved CRT-based image watermarking method in the DCT domain is proposed. The proposed method provides better robustness which decreases changes of absolute difference of residues against rounding errors due to DCT conversion and various attacks. Experimental results show that the proposed method has a good robustness against various attacks compared with the conventional CRT-based watermarking in DCT domain.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2072-2075
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• 2003

This paper is studied the high speed processing moving picture encodec to compress and encode a moving picture by real time. This is used the new motion vector search algorithm with smallest search point in H.263 encodec, and is applied the integer DCT for the encodec by converting a moving picture. The integer DCT behaves DCT by the addition operation of the integer using WHT and a integer lifting than conventional DCT that needs the multiplication operation of a floating point number. Therefore, the integer DCT can reduce the operation amount than basis DCT with having an equal PSNR because the multiplication operation of a floating point number does not need.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1069-1074
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• 2008

This paper presents an efficient architecture for $2^n$-point DCT algorithm. The proposed approach makes use of the fact that, in most DCT applications, the scaling operation in the DCT unit can be eliminated and combined with the scaling operation in the quantizer unit. This important property is efficiently exploited with the CORDIC(COordinate Rotation DIgital Computer) algorithm to produce a regular architecture suitable for VLSI implementation. Although there have been several attempts to exploit CORDIC algorithm in developing DCT architectures, the proposed approach provides the most efficient way for scaled DCT applications by completely eliminating the scale factor compensation.

• Journal of Korea Multimedia Society
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• v.6 no.6
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• pp.962-967
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• 2003

In this paper, we proposed DC term embedding digital watermarking in the DCT domain. We computed a 8${\times}$8 block DCT The watermark signal is composed of a random number sequence of length 1000, which obeys normal distribution with zero mean and unit variance N(0,1). We embedded watermark signal in DC term for small watermark signal, the other watermark signal embedded in the largest AC coefficients. Experiment show that the invisibility and robust of the proposed method better than those of the conventional methods.