• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.433-436
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• 2003

In this paper, the efficient motion estimation and compensation method for 3 dimensional wavelet transform is proposed. Recently, since the compression performance and scalable functionality are provided by wavelet transform, many researches have been carried out for applying to the video compression. For the temporal filtering, motion estimation and compensation techniques are used, but the unconnected pixels, which are produced by motion compensation result into the degradation of coding performance and quality of the picture. For the efficient motion compensated temporal filtering by reducing the number of these unconnected pixels, we propose the variable block size motion estimation and compensation method. Also we propose a method that determines the block size using rate-distortion optimization technique according to the local characteristics of the frame. The simulation results show the improved performances than the MPEG-4 scalable coding methods and the 3 dimensional wavelet coding methods using fixed block size motion estimation and compensation.

• The Magazine of the IEIE
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• v.24 no.9
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• pp.91-98
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• 1997

Text-to-Speech(WS) technology has been attracting a lot of interest among speech engineers because of its own benefits. Namely, the possible application areas of talking computers, emergency alarming systems in speech, speech output devices for speech-impaired, and so on. Hence, many researchers have made significant progresses in the speech synthesis techniques in the sense of their own languages and as a result, the quality of current speech synthesizers are believed to be acceptable to normal users. These are partly why the MPEG group had decided to include the WS technology as one of its MPEG-4 functionalities. ETRI has made major contributions to the current MPEG-4 775 appearing in various MPEG-4 documents with relatively minor contributions from AT&T and NW. Main MPEG-4 functionalities presently available are; 1) use of original prosody for synthesized speech output, 2) trick mode functions for general users without breaking synthesized speech prosody, 3) interoperability with Facial Animation(FA) tools, and 4) dubbing a moving/anlmated picture with lip-shape pattern informations.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.699-707
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• 1999

It cannot be argued that speech is the most natural interfacing tool between men and machines. In order to realize acceptable speech interfaces, highly advanced speech recognizers and synthesizers are inevitable. Text-to-Speech(TTS) technology has been attracting a lot of interest among speech engineers because of its own benefits. Namely, the possible application areas of talking computers, emergency alarming systems in speech, speech output devices fur speech-impaired, and so on. Hence, many researchers have made significant progresses in the speech synthesis techniques in the sense of their own languages and as a result, the quality of currently available speech synthesizers are believed to be acceptable to normal users. These are partly why the MPEG group had decided to include the TTS technology as one of its MPEG-4 functionalities. ETRI has made major contributions to the current MPEG-4 TTS among various MPEG-4 functionalities. They are; 1) use of original prosody for synthesized speech output, 2) trick mode functions fer general users without breaking synthesized speech prosody, 3) interoperability with Facial Animation(FA) tools, and 4) dubbing a moving/animated picture with lib-shape pattern information.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.10
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• pp.99-111
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• 1994

A motion picture compression scheme using subband coding with motion compensation is presneted in this paper. A hierarchical subband decomposition is used to split the image signal into 10 subbands with a 3-layer pyramid structure and motion compensation is used in each band. However, in this case, motion vector information is drastically increased; therefore, initial motion vectors are estimated in the highest pyramid and motion vectors are refined using the reconsructed subband signal in each layer. Simulation results show that the proposed method compares favorably in terms of prediction error energy and side informatio with methods requiring additional information. Images recostructed from the proposed method show good quality compared to those reconstructed using blockwise DCT.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1640-1643
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• 2002

Image sticking, the phenomenon that the previously displayed pattern still remains after the image is changed into different image, is one of the most serious problem in realizing high picture quality. In this paper, we tried characterizing this undesirable feature in terms of the luminance and the intial firing voltage at ramp up time in reset period. It was found that the cell located at the boundary of previous image pattern show low firing voltage and high background luminance. And the results show that the degree of the image sticking is severely affected by discharge duration and the length of the sustain period.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.69-74
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• 1995

An object color can be seen differently under the various outer illuminants. However, human visual system has color constancy that the object color can be seen constantly under the different outer illuminants. When the viewer watches TV under specific outer illuminants, he perceives distorted color due to the emitting spectrum of outer illuminants as well as the radiation of CPT itself. Namely, when the outer illuminants such as fluorescent and incandescent lamps incident on CPT, brightness, saturation, hue, and contrast on color pictures are changed, he perceives distorted color from the original color. In this paper color enhancement algorithm based on light intensity and outer light decision function using RGB sensor was proposed. The implemented TV of proposed algorithm has higher visual quality at the view point of human visual system and more vivid than that of conventional color TV.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.06a
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• pp.31-36
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• 1997

Bit allocation is a critical problem in video encoding such as MPEG. To improve the quality of the reconstructed sequence for a given bit rate, the assigned target bits for a group of pictures (GOP) must be allocated to each picture efficiently. In this paper, we derive a target bit allocation algorithm for more efficient rate control, by assuming that the average rate-distortion curve for an input source is logarithmic. This target bit allocation is based on Shannon's rate-distortion theory, which deals with the minimization of source distortion subject to a channel rate constraint. Simulation results show that the proposed target bit allocation algorithm provides better performance than the one in MPEG-2 Test Model 5 (TM5).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.181-186
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• 1997

Transcoding is the key technique to further reduce the bit-rate of a previously compressed video. The performance of the transcoding is evaluated by the two factors, the accuracy on the target bit-rate and the complexity of the implementation. In this paper, were propose a new rate control algorithm which has very accurate bit-rate control performance and much smaller computational complexity. For the accuracy problem, we empirically observe the relationship between the quantization step size and generated bits in requantization process and then find that the relationship can be characterized as the new piece-wise linear model. For the complexity problem, we reduce the role of feedback rate control. The simulation results show that the proposed method gives the better performance in the accuracy with the same picture quality than conventional rat control algorithm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.16.2-21
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• 1998

Old movies are often corrupted by randomly located blotches and scratches. In this paper were present an efficient method for detection and removal of these distortions. The presented method is composed of two separate steps: the detection process and the restoration process. In the detection process, blotch locations are detected through global motion segmentation, the sequential approach to motion segmentation, a robust model-fit criterion and so on, we form the algorithm for the algorithm for the global motion segmentation tuned to the blotch detection problem. In the restoration process, the missing data of the detected blotch areas are temporally extrapolated from the corresponding image areas at the preceding or the succeeding image frame with considering the global motion segmentation results. We apply the presented method to moving image sequences distorted by artificial blotches. The method works very well and provides a subjective improvement of picture quality.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.75-76
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• 2000

Tone reproduction characteristics of color and gray have a great influence on the picture quality in visual display. In this study, we optimized tone reproduction characteristics of color and gray of CRT monitor by setting brightness to the optimum level, in which offsets for RGB channels can be assumed to zero. The optimum brightness level could be found by measuring a few tones of neutral for the combination of 2 levels of brightness and 2 levels of contrast. As the result, the relationship between normalized DAC count and normalized luminance of primary color or gray has been simply presented by gamma and result in good phosphor constancy.