• Journal of KIISE:Computing Practices and Letters
• /
• v.11 no.1
• /
• pp.50-61
• /
• 2005

To provide adaptively video streaming services on network environment, video transcoding is introduced. The one of transcoding methods is the frame-rate conversion. it needs a re-estimation about a motion vector of the frame to refer a skipping frame. This re-estimation makes higher the computational complexity in video transcoding. To reduce the computational complexity of a motion vector refinement, this paper proposes a region & activity based motion vector composition scheme that refine the moving vector of a skipping frame. This scheme composes each motion vector from the weight based on the activity information of a macroblock and the site of the overlapped area. The experiment result shows that RABVC has a higher PSNR than the value of existing weight-based motion vector selection schemes though the computational complexity of our scheme is similar to that of other schemes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.1C
• /
• pp.37-47
• /
• 2009

When H.264 encoded video streams are transmitted over wireless network, packet loss is unavoidable. Responding on this environment, we propose methods to recover missed motion vector in the decoder: At first, A candidate vector set for missing macroblock is estimated from high correlation coefficient of neighboring motion vectors and missing block vectors the algorithm clusters candidate vectors through distances amongst motion vectors of neighboring blocks. Then the optimal candidate vector is determined by the median value of the clustered motion vector set. In next stage, from the candidate vector set, the final candidate vector of missing block is determined it has minimum distortion value considering directions of neighboring pixels' boundary. Test results showed that the proposed algorithm decreases the candidate motion vectors $23{\sim}61%$ and reduces $3{\sim}4sec$ on average processing(decoding) time comparing the existing H.264 codec. The PSNR, in terms of visual quality is similar to existing methods.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1999.11b
• /
• pp.109-114
• /
• 1999

Due to the temporal correlation of the image sequence, the motion vector of a block is highly related to the motion vector of the same coordinate block in the previous image frame. If we can obtain useful and enough information from the motion vector of the same coordinate block of the previous image frames, the total number of search points used to find the motion vector of the current block may be reduced significantly. Using that idea, an efficient new predicted direction search algorithm (PDSA) for block matching motion estimation is proposed in this paper.

• Journal of the Korea Computer Industry Society
• /
• v.5 no.9
• /
• pp.987-992
• /
• 2004

There is the temporal correlation of the video sequence between the motion vector of current block and the motion vector of previous block. In this paper, we propose the improved diamond search pattern using an motion vector prediction candidate search point by the predicted motion information from the same block of the previous frame. Simulation results show that PSNR(Peak-to-Signal Noise Ratio) values are improves as high as high as 14~24% in terms of average number of search point per motion vector estimation and improved about 0.02~0.37dB on an average except the full search(FS) algorithm.

• Proceedings of the KIEE Conference
• /
• 1999.11c
• /
• pp.745-747
• /
• 1999

디지털 TV의 동영상 표준인 MPEG2는 방대한 양의 디지털 데이터를 발생한다. 그러나 현재 사용하고 있는 디지털 저장 매체의 수용 능력에는 한계가 있으므로 저장을 위해 전송된 high bit rate의 MPEG2 bitstream을 더욱 낮은 bit rate의 bitstream으로 전환하는 transcoding 기법이 반드시 필요하다. 기존의 encoder와 decoder를 이용하여 구현 가능한 장점이 있는 cascade transcoder는 reencoding시 motion estimation에 많은 수행 시간이 소요되므로, motion estimation 과정을 최소화하면서 optimal motion vector를 구할 수 있는 motion vector refinement 기법을 MPEG2 cascade transcoder에 적용하였다. 결과 처리 속도는 3-5배 향상되었고 화질은 기존의 72 transcoder에 비해 평균 0.1dB 이상의 FSNR 향상이 있었다. 또한 1Mbps와 같은 low bit rate에서 더욱 큰 화질 향상이 있었다.

• Journal of Broadcast Engineering
• /
• v.17 no.2
• /
• pp.252-261
• /
• 2012

This papers proposes a motion vector coding method which selects the optimal predictive motion vector after excluding some candidate predictive motion vectors in the minimum rate-distortion sense, and prunes the candidate predictive motion vectors by a contradiction testing that operates under a predefined criterion at both encoder and decoder for reducing the signaling information. Experimental results show that the proposed method gains in BDBR by up to 1.8% compared to the H.264/AVC.

• Journal of Korea Multimedia Society
• /
• v.15 no.6
• /
• pp.731-736
• /
• 2012

Latest digital cinema is getting more interest on recent days. The combination of visually immersive 3D movie with chair movements and other physical effects has added more enjoyment. The movement of the chair is controlled manually in these digital cinemas. By the analysis of the digital cinema's video sequences, movement of the chair can be controlled automatically. In the proposed method first of all the motion of focused object and the background is identified and then the motion vector information is extracted by using the 9-search range. The motion vector is determined only for the movement of background while the object is stationary. The extracted Motion information from the digital cinemas is used for the movement control of the chair. The experimental results show that the proposed method outperforms the existing methods in terms of accuracy.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.1
• /
• pp.428-435
• /
• 2017

In this paper, we propose a novel motion field estimation algorithm for which a U-disparity map and forward-and-backward error removal are applied in a vehicular environment. Generally, a motion exists in an image obtained by a camera attached to a vehicle by vehicle movement; however, the obtained motion vector is inaccurate because of the surrounding environmental factors such as the illumination changes and vehicles shaking. It is, therefore, difficult to extract an accurate motion vector, especially on the road surface, due to the similarity of the adjacent-pixel values; therefore, the proposed algorithm first removes the road surface region in the obtained image by using a U-disparity map, and uses then the optical flow that represents the motion vector of the object in the remaining part of the image. The algorithm also uses a forward-backward error-removal technique to improve the motion-vector accuracy and a vehicle's movement is predicted through the application of the RANSAC (RANdom SAmple Consensus) to the previously obtained motion vectors, resulting in the generation of a motion field. Through experiment results, we show that the performance of the proposed algorithm is superior to that of an existing algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.895-898
• /
• 2003

The higher precision is demanded in modem manufacturing and it requires the more accurate servo controller. Cross-coupling control (CCC) has been developed to improve contouring motion. In this paper we introduce a new nonlinear CCC that is based on contour-error-vector using a parametric curve interpolator. A vector from the actual tool position to the nearest point on the desire path is directly adopted. The contour-error-vector is determined by constructing a tangential vector of nearest point on desired curve and determining the vector perpendicular to this tangential vector from the actual tool position. Moreover, the vector CCC can apply directly and easily to free-form curves include convex and concave form. The experimental results on a three-axis CNC machine center show that the present approach significantly improves motion accuracy in multi-axis motion

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.53 no.8
• /
• pp.602-605
• /
• 2004

A novel motion vector re-estimation technique for transcoding into lower spatial resolution is proposed. This technique is based on the fact that the block matching error is proportional to the complexity of the reference block with Taylor series expansion. It is shown that the motion vectors re-estimated by the proposed method are closer to optimal ones and offer better quality than those of previous techniques.