8,143 research outputs found
Adaptive rate control scheme for very low bit rate video coding
No full textIn video coding systems, an effective rate control method is one of the most important issues for the good video quality. This paper presents an adaptive rate control scheme based on buffer fullness, quantization, and buffer utilization for very low bit rate communication lines, such as 16kbit/s, 32kbit/s, and so on. The strategy is implemented on H.263, which is a video coding algorithm for narrow band telecommunication channels up to 64kbit/s recommended by ITU-T SG15, to show the effectiveness. The simulation result shows that the suggested rate control scheme has better SNR performance and buffer utilization of source coder than those of linear and non-linear[11] buffer control strategies
Block-matching algorithm based on an adaptive reduction of the search area for motion estimation
No full textThe motion estimation and compensation technique is widely used for video coding applications but the real-time motion estimation is not easy due to its enormous computations. In this paper, a new adaptive reduction of search area for the block-matching algorithm is presented to reduce the computational complexity of the full search block-matching algorithm for low bit-rate video coding. The proposed method exploits the correlation of successive video frames and adjusts the size of search area depending on the displaced block difference and the block classification information in the previous frames of the block. Simulation-results show that the proposed algorithm has similar mean square error performance to the full search block-matching algorithm but only requires less a half computational complexity than the full search algorithm. (C) 2000 Academic Press
Adaptive adjustment of the search window for block-matching algorithm with variable block size
No full textThe motion estimation and compensation technique is widely used for video coding applications but it is hard to implement the real-time video codec due to its enormous computations. In this pater, an adaptive adjustment of the search window for block-matching algorithm(BMA) with variable size of the block is presented to reduce the computational complexity of full search BMA(FSBMA). The size of the search window is adjusted by using the block similarity and the displaced block difference(DBD). Experiments with test video sequences show that the presented scheme has good MSE performance and less complexity compared with FSBMA and other previous works
Adaptive adjustment of the search window for block-matching algorithm with variable block size
No full textCrystal structure and enzyme mechanism of Delta(5)-3-ketosteroid isomerase from Pseudomonas testosteroni
No full textBacterial Delta(5)-3-ketosteroid isomerase (KSI) from Pseudomonas testosteroni has been intensively studied as a prototype for understanding an enzyme-catalyzed allylic rearrangement involving intramolecular proton transfer. Asp(38) serves as a general base to abstract the proton from the steroid C4-H, which is a much stronger base than the carboxyl group of this residue. This unfavorable proton transfer requires 11 kcal/mol of energy which has to be provided by favorable interactions between catalytic residues and substrate in the course of the catalytic reaction. How this energy is provided at the active site of KSI has been a controversial issue, and inevitably the enzyme mechanism is not settled. To resolve these issues, we have determined the crystal structure of this enzyme at 2.3 Angstrom resolution. The crystal structure revealed that the active site environment of P. testosteroni KSI is nearly identical to that of Pseudomonas putida KSI, whose structure in complex with a reaction intermediate analogue we have determined recently. Comparison of the two structures clearly indicates that the two KSIs should share the same enzyme mechanism involving the stabilization of the dienolate intermediate by the two direct hydrogen bonds to the dienolate oxyanion, one from Tyr(14) OH and the other from Asp(99) COOH. Mutational analysis of the two residues and other biochemical data strongly suggest that the hydrogen bond of Tyr(14) provides the more significant contribution than that of Asp(99) to the requisite 11 kcal/mol of energy for the catalytic power of KSI
Composite robot end effector for manipulating large LCD glass panels
No full textRecently, the design and the manufacture of light robot end effecters with high stiffness have become important in order to reduce the deflection due to the self-weight and weight of glass panel, a part of LCD, as the size of glass panels as well as robot end effecters increases. The best way to reduce the deflection and vibration of end effectors without sacrificing the stiffness of end effectors is to employ fiber reinforced composite materials for main structural materials because composite materials have high specific stiffness and high damping. In this work, the end effector for loading and unloading large glass panels were designed and manufactured using carbon fiber epoxy composite honeycomb sandwich structures. Finite element analysis was used along with an optimization routine to design the composite end effector. A box type sandwich structure was employed to reduce the shear effect arising from the low modulus of honeycomb structure. The carbon fiber epoxy prepreg was hand-laid up on the honeycomb structure and cured in an autoclave. A special process was used to reinforce the two sidewalls of the box type sandwich structure. The weight reduction of the composite end effector was more than 50% compared to the weight of a comparable aluminum end effector. From the experiments, it was also found that the static and dynamic characteristics of the composite end effector were much improved compared to those of the aluminum end effector. (C) 2000 Published by Elsevier Science Ltd
Block-matching criterion for efficient VLSI implementation of motion estimation
No full textA new block-matching motion estimation criterion is presented, which can be implemented in VLSI more efficiently than the conventional criterion. The proposed scheme can reduce the amount of hardware required and increase the speed of computation in a VLSI chip with acceptable video performance. Video performance and VLSI implementation using the proposed criterion are presented
An efficient block-matching criterion for motion estimation and its VLSI implementation
No full textThe block-matching motion estimation is the most popular technique for motion compensated coding of image sequence. Due to the intensive computational requirement to perform motion estimation(ME) in real-time, application specific VLSI implementation of the ME is indispensable. In this paper, we present a novel block-matching criterion for motion estimation called Reduced Bits Mean Absolute Difference(RBMAD). By comparison with conventional schemes, our scheme reduces hardware requirement and increases the speed of computation in VLSI chip with acceptable video performance. We describe in details the video performances of proposed criterion and conventional ones. We also show our VLSI implementation using the proposed scheme to compare the hardware requirement and operating speed with conventional ones. It is found that RBMAD using 4bits has reasonable video performance with 57% less VLSI area and 34% faster, thus it is suitable for low cost applications of video coding
Adaptive bit-reduced mean absolute difference criterion for block-matching algorithm and its VLSI design
No full textAn adaptive bit-reduced mean absolute difference (ABRMAD) is presented as a criterion for the block-matching algorithm (BMA) to reduce the complexity of the very large scale integration (VLSI) implementation and to improve the processing time. The ABRMAD uses the lower pixel resolution of the significant bits instead of full-resolution pixel values to estimate the motion vector (MV) by examining the pixels in a block. Simulation results shaw that the 4-bit ABRMAD has competitive mean square error (MSE) results and a half less hardware complexity than the mean absolute difference (MAD) criterion. It has also better characteristics in terms of both MSE performance and hardware complexity than the MiniMax criterion and has better MSE performance than difference pixel counting (DPC), binary block matching with edge map (BBME), and bit-plane matching (BPM) with the same number of bits. (C) 1998 Society of Photo-Optical instrumentation Engineers. [S0091-3286(98)02112-6]
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