• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.56-62
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• 2009

In H.264/AVC, rate distortion optimization algorithm is used to decide the best block mode from various block modes. It improves a bit rate but greatly increases an amount of computation. This paper proposes a fast rate distortion optimization algorithm that omits a rate distortion optimization adaptively by predicting its cost from the cost calculated for motion estimation. The simulation results show that the proposed algorithm, on average, keeps nearly the image quality and the bit rate made by the rate distortion optimization while reduces 69.86% and 69.63% of computation added by it in CIF and QCIF respectively.

• Journal of Multimedia Information System
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• v.4 no.4
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• pp.311-316
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• 2017

High Efficiency Video Coding (HEVC) is the newest video coding standard for improvement in video data compression. This new standard provides a significant improvement in picture quality, especially for high-resolution videos. A quadtree-based structure is created for the encoding and decoding processes and the rate-distortion (RD) cost is calculated for all possible dimensions of coding units in the quadtree. To get the best combination of the block an optimization process is performed in the encoder, called rate distortion optimization (RDO). In this work we are proposing a novel approach to enhance the overall RDO process of HEVC encoder. The proposed algorithm is performed in two steps. In the first step, like HEVC, it performs general rate distortion optimization. The second step is an extra checking where a SSIM based cost is evaluated. Moreover, a fast SSIM (FSSIM) calculation technique is also proposed in this paper.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.323-326
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• 2005

Several video coding standards, such as MPEG-4 and H.263, have been investigated to reduce the resulting number of bits while pursuing the maximum video quality. The recent video coding standard, H.264, provides higher coding efficiency than previous coding standards by using the mode decision scheme. For mode decision, H.264 chooses the best macroblock mode among the several candidates using Lagrangian cost function which reflects both the rate and the distortion. H.264 employs only one rate-distortion optimization (RDO) model for all macroblocks. Since the characteristics of each macroblock is different, each macroblock should have its own RDO model. In this paper, we propose an adaptive rate-distortion optimization algorithm for H.264. We regulate the Lagrangian multiplier considering the picture type and characteristics of each macroblock.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.999-1002
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• 2005

This paper describes an improved Rate-Distortion Optimization Algorithm for JPEG2000. We proposed a new optimal constant setting method and rate allocation method to reduce execution time of the rate control. And we proposed hardware structure of the improved R-D opti. algorithm. Consequently, improved Rate-Distortion Optimization algorithm is faster than conventional rate control scheme in JPEG2000 standard and have nearly same performance.

• Journal of information and communication convergence engineering
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• v.5 no.1
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• pp.54-58
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• 2007

A real-time frame-layer rate control algorithm with a token bucket traffic shaper is proposed for distortion variation minimization. The proposed rate control method uses a non-iterative optimization method for low computational complexity, and performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. The proposed algorithm does not produce time delay from encoding, and is suitable for real-time low-complexity video encoder. Experimental results indicate that the proposed control method provides better visual and PSNR performances than the existing rate control method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.165-173
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• 2004

H.264 is the newest international video coding standard that provides high coding efficiency. A macroblock in H.264 has 7 different motion-compensation block sizes in the Inter mode, and several different prediction directions in the Intra mode. In order to achieve as highest coding efficiency as possible, H.264 reference model employs complex mode decision technique based on rate-distortion (RD) optimization which requires high computational complexity. In this paper, we propose two techniques -'early SKIP mode decision' and 'selective intra mode decision' - which can further reduce the computational complexity. Simulation results show that without considerable performance degradation, the proposed methods reduce encoding time by 30% on average and save the number of computing rate-distortion cost by 72%.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.3 s.309
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• pp.50-58
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• 2006

This paper describes the implementation of an efficient Rate-Distortion Optimization algerian to speed up rate control in JPEG2000. While the conventional algorithm determines the rate constant by averaging maximum R-D slope and minimum R-D slope for entire image, the proposed algorithm determines it by using R-D slopes of coding passes located near truncation point. Moreover, the rate allocation in proposed algorithm is conducted about only coding passes excluded from the previous rate allocation. As a result, it can reduce the number of operations required for rate-distortion optimization. The proposed algorithm was implemented in C programing language and was executed on the Altera Excalibur(EPXA4) development board.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.591-597
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• 2008

In this paper, we present a improved rate distortion optimization (RDO) for H.264 intra coding. By using new mode decision criteria pass for $I4{\times}4$ in company with the original RDO, the proposed method can achieve the better coding efficiency comparing with the original RDO. Our experimental results show that the proposed algorithm can archive about $0.64{\sim}1.6578%$ bit rate decrease at the same PSNR and $0.049{\sim}0.101dB$ PSNR increase at the same bit rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.435-449
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• 2023

The state-of-the-art video-based point cloud compression(V-PCC) has a high efficiency of compressing 3D point cloud by projecting points onto 2D images. These images are then padded and compressed by High-Efficiency Video Coding(HEVC). Pixels in padded 2D images are classified into three groups including origin pixels, padded pixels and unoccupied pixels. Origin pixels are generated from projection of 3D point cloud. Padded pixels and unoccupied pixels are generated by copying values from origin pixels during image padding. For padded pixels, they are reconstructed to 3D space during geometry reconstruction as well as origin pixels. For unoccupied pixels, they are not reconstructed. The rate distortion optimization(RDO) used in HEVC is mainly aimed at keeping the balance between video distortion and video bitrates. However, traditional RDO is unreliable for padded pixels and unoccupied pixels, which leads to significant waste of bits in geometry reconstruction. In this paper, we propose a new RDO scheme which takes 3D-Distortion into account instead of traditional video distortion for padded pixels and unoccupied pixels. Firstly, these pixels are classified based on the occupancy map. Secondly, different strategies are applied to these pixels to calculate their 3D-Distortions. Finally, the obtained 3D-Distortions replace the sum square error(SSE) during the full RDO process in intra prediction and inter prediction. The proposed method is applied to geometry frames. Experimental results show that the proposed algorithm achieves an average of 31.41% and 6.14% bitrate saving for D1 metric in Random Access setting and All Intra setting on geometry videos compared with V-PCC anchor.

• Journal of Welding and Joining
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• v.21 no.7
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• pp.42-48
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• 2003

Welding distortion is a current issue in many industrial parts, especially for heavy industry such as shipbuilding, plant industry. The welding process has many processing parameters influencing welding angular distortion such as heat input power, welding speed, gas flow rate, plate thickness and the welded material properties, etc. In this work, the conventional local minimization concept was applied to find a set of optimum welding process parameters, consisted of welding speed, plate thickness and heat input, for a minimum angular distortion. An analytic solution for welding angular distortion, which is based on laminated plate theory, was also applied to investigate and optimize the welding process parameters. The optimized process parameters and the angular distortion for various parametric conditions could be easily found by using the local minimum concept.