• Journal of Broadcast Engineering
• /
• v.15 no.3
• /
• pp.426-433
• /
• 2010

The H.264/AVC video coding standard performs inter prediction using variable block sizes to improve coding efficiency. Since we predict not only the motion of homogeneous regions but also the motion of non-homogeneous regions accurately using variable block sizes, we can reduce residual information effectively. However, each motion vector should be transmitted to the decoder. In low bit rate environments, motion vector information takes approximately 40% of the total bitstream. Thus, motion vector competition was proposed to reduce the amount of motion vector information. Since the size of the motion vector difference is reduced by motion vector competition, it requires only a small number of bits for motion vector information. However, we need to send the corresponding index of the best motion vector predictor for decoding. In this paper, we propose a new codeword table based on the phased-in code to encode the index of motion vector predictor efficiently. Experimental results show that the proposed algorithm reduces the average bit rate by 7.24% for similar PSNR values, and it improves the average image quality by 0.36dB at similar bit rates.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.1
• /
• pp.91-96
• /
• 2010

Concentric mosaics are made with arranging and summing of video frames by using common spacial standards. Compared with previous works on 3-D wavelet transform coding, we have made important design considerations to enable flexible partial decoding and bit-stream random access. A just-in-time(JIT) rendering engine of the compressed concentric mosaic is developed. However, computationally, it is still demanding to accomplish the real-time rendering. Only the contents for specific scene representation are need to be decoded by maintaining compressed data. Thus our proposed algorithm is able to render real concentric mosaic by using lifting scheme instead of wavelet transform.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2006.11a
• /
• pp.67-70
• /
• 2006

디스플레이 장치와 영상 기술의 발전으로 3D 입체 영상에 대한 관심과 기술적 접근이 어느 때 보다 활발하다. 입체 영상의 경우 통상 복수의 평면 영상을 이용하여 합성하게 되는데 이 과정에서 각 영상의 객관적 화질을 서로 달리 함으로써 주관적 화질을 향상시킬 수 있다는 연구가 진행되어 왔다. 그러나 객관적 화질을 지나치게 달리 하거나 전반적으로 낮은 화질의 영상에서는 경계선이 제대로 재현되지 않아 입체감을 떨어뜨리는 문제가 발생한다. 또한 기존의 연구는 스테레오 영상에 한해서만 위의 가설을 검증하였으나 최근의 입체 영상에 관한 연구는 스테레오 영상뿐만 아니라 다시점 영상에서도 활발히 진행되고 있다. 본 논문에서는 스테레오 영상과 9시점 영상에서의 비대칭 영상 부호화가 주관적 화질에 미치는 영향을 검증하고 구체적으로 어느 정도의 객관적 화질 차이를 유지하는 것이 비대칭 부호화에서 가장 효율적인지를 밝힌다. 또한 기존의 비대칭 영상 부호화와 비교하여 주관적 화질을 개선할 수 있는 더욱 효율적인 알고리듬을 제안한다. 제안되는 알고리듬은 경계선의 강도를 기준으로 매크로블록의 양자화 파라미터를 달리 하여 영상의 경계선을 보호하는 방법으로써 기존의 비대칭 영상 부호화보다 더욱 향상된 주관적 화질을 얻을 수 있다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.5 no.4
• /
• pp.450-456
• /
• 2010

In the high-speed packet service, next generation mobile communication system has emerged as a major feature. If the fire of these high-speed kit services and non-continuous transmission of data due to the symmetrical nature of daeyiteo traffic for D-CDMA system has been actively studied. Small amounts of data moving in the uplink, but the real-time video downlink transmission, such as downloading large files to move data and services to those with asymmetric traffic characteristics, a system that can efficiently handle the data requirements be. Of 3GPP TDD(Time Division Duplex) scheme based on CDMA and TDMA in a way by introducing the concept through the proper allocation of time slots that can handle asymmetric traffic efficiently, has an advantage. TD-CDMA system by considering the characteristics of the frame configuration of transmission methods, such as physical channel structure and channel coding has been investigated. In addition, the HARQ scheme TD-CDMA system performance is analyzed by comparing them.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.3C
• /
• pp.307-314
• /
• 2003

In the general multiple video object coder, more interested objects such as speaker or moving object is consistently coded with higher priority. Since the priority of each object may not be fixed in the whole sequence and be variable on frame basis, it must be adjusted in a frame. In this paper, we analyze the independent rate control algorithm and global algorithm that the QP value is controled by the static parameters, object importance or priority, target PSNR, weighted distortion. The priority among static parameters is analyzed and adjusted into dynamic parameters according to the visual interests or importance obtained by camera interface. Target PSNR and weighted distortion are proportionally derived by using magnitude, motion, and distortion. We apply those parameters for the weighted distortion control and the priority-based control resulting in the efficient bit-rate distribution. As results of this paper, we achieved that fewer bits are allocated for video objects which has less importance and more bits for those which has higher visual importance. The duration of stability in the visual quality is reduced to less than 15 frames of the coded sequence. In the aspect of PSNR, the proposed scheme shows higher quality of more than 2d13 against the conventional schemes. Thus the coding scheme interfaced to human- eye proves an efficient video coder dealing with the multiple number of video objects.

• Journal of Satellite, Information and Communications
• /
• v.8 no.4
• /
• pp.75-80
• /
• 2013

In this paper, the Ka-band maritime satellite communication systems for mobile terminals are proposed. The design includes the link budget analysis, determination of modulation and coding schemes and the overall structure of a transmitter. To avoid the harmful effects on the existing DVB-S2 services, the proposed maritime satellite system using the same spectrum with DVB-S2 at the same time employs the very wideband spreading transmission. Additionally, omni-directional low-gain antennas should be equipped in a mobile terminal to reduce the system cost. These two considerations limit the maximum transmission rate of the proposed system. Due to the limitations, the proposed system includes 36 dB or 39 dB spreading gain depending on the modulation scheme and a link-adaptive repetition method depending on the level of rain attenuation. To support short packets with minimal performance loss, the turbo code used in 3GPP instead of LDPC(low density parity check code) is adopted. By combining them, the overall structure of low-rate maritime satellite communication system is designed.

• Annual Conference of KIPS
• /
• 2005.11a
• /
• pp.743-746
• /
• 2005

본 논문에서는 디지털 비디오 인코딩 과정의 VLC(variable length coding) 영역에서 블록계층의 DC/AC 성분을 이용한 인증과 서명의 이중 비디오 워터마킹 시스템을 제안하였다. 제안한 기법은 블록계층의 DC 성분과 AC 성분에서 HVS(human visual system)의 특성을 고려한 것이다. 인증 워터마킹은 주요한 정보를 포함하는 저주파 영역과 윤곽선 정보를 포함하는 중간 주파수 영역을 이용하여 인트라 프레임의 DC 성분과 움직임 벡터의 부호를 변형시켰고, 서명 워터마킹은 모든 프레임의 AC 성분들 중에서 마지막 AC 성분의 Level이 '1'인 경우에만 워터마크를 삽입하였다. 서명 워터 마크 검출은 저작권자의 비밀 키에 의해서만 가능하고, 기술적인 면에서 저자권자의 판별 기준이 될 수 있다. 제안한 이중 비디오 워터마킹 시스템의 특징은 인증과 서명의 두 가지 기능을 선택적으로 수행할 수 있으며, 계산과정이 복잡하지 않으면서 비트 스트림(bit-stream)을 유지시킨다. 그리고 실험 결과에서 기존의 방법보다 화질 면에서 $2{\sim}3dB$ 더 높은 수치를 얻어 우수함을 보였고, 인코딩 수행 속도에 미치는 영향은 거의 없었으며, 향후 실시간 인코딩 처리에 응용될 수 있다.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.12 no.4
• /
• pp.1-12
• /
• 2016

Digital imaging technology has developed into a state-of-the-art IT convergence, composite industry beyond the limits of the multimedia industry, especially in the field of smart object recognition, face - Application developed various techniques have been actively studied in conjunction with the phone. Recently, face recognition technology through the object recognition technology and evolved into intelligent video detection recognition technology, image recognition technology object detection recognition process applies to skills through is applied to the IP camera, the image object recognition technology with face recognition and active research have. In this paper, we first propose the necessary technical elements of the human factor technology trends and look at the human object recognition based spFACS (Smile Progress Facial Action Coding System) for detecting smiles study plan of the image recognition technology recognizes objects. Study scheme 1). ASM algorithm. By suggesting ways to effectively evaluate psychological research skills through the image object 2). By applying the result via the face recognition object to the tooth area it is detected in accordance with the recognized facial expression recognition of a person demonstrated the effect of extracting the feature points.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.46 no.3
• /
• pp.68-74
• /
• 2009

In this paper, we propose an effective memory reduction algorithm to reduce the amount of reference frame buffer and memory bandwidth in video encoder and decoder. In general video codecs, decoded previous frames should be stored and referred to reduce temporal redundancy. Recently, reference frames are recompressed for memory efficiency and bandwidth reduction between a main processor and external memory. However, these algorithms could hurt coding efficiency. Several algorithms have been proposed to reduce the amount of reference memory with minimum quality degradation. They still suffer from quality degradation with fixed-bit allocation. In this paper, we propose an adaptive block-based min-max quantization that considers local characteristics of image. In the proposed algorithm, basic process unit is $8{\times}8$ for memory alignment and apply an adaptive quantization to each $4{\times}4$ block for minimizing quality degradation. We found that the proposed algorithm can obtain around 1.7% BD-bitrate gain and 0.03dB BD-PSNR gain, compared with the conventional fixed-bit min-max algorithm with 37.5% memory saving.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.5A
• /
• pp.503-509
• /
• 2007

Low-power motion estimation is required for video coding in portable information devices. In this paper, we propose a low-power motion estimation algorithm and 1-D systolic may VLSI architecture using full search block matching algorithm (FSBMA). Main power dissipation sources of FSBMA are complex computations and frequent memory accesses for data in the search area. In the proposed algorithm, memory accesses and computations are reduced by using 1D PE (processing array) array architecture performing motion estimation of two neighboring blocks in parallel and by skipping unnecessary computations during motion estimation. The VLSI implementation results of the algorithm show that the proposed VLSI architecture can save 9.3% power dissipation and can operate two times faster than an existing low-power motion estimator.