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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Broadcast Engineering
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The Korean Institute of Broadcast and Media Engineers
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Volume & Issues
Volume 17, Issue 6 - Nov 2012
Volume 17, Issue 5 - Sep 2012
Volume 17, Issue 4 - Jul 2012
Volume 17, Issue 3 - May 2012
Volume 17, Issue 2 - Mar 2012
Volume 17, Issue 1 - Jan 2012
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Spatial Correlation Based Fast Coding Depth Decision and Reference Frame Selection in HEVC
Lee, Sang-Yong ; Kim, Dong-Hyun ; Kim, Jae-Gon ; Choi, Hae-Chul ; Kim, Jin-Soo ; Choi, Jin-Soo ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 716~724
DOI : 10.5909/JBE.2012.17.5.716
In this paper, we propose a fast decision method of maximum coding depth decision and reference frame selection in HEVC. To reduce computational complexity and encoding time of HEVC, two methods are proposed. In the first method, the maximum depth of each coding unit (CU) in a largest CU (LCU) is constrained by using the maximum coding depth used by adjacent LCUs based on the assumption that the spatial correlation is very high and rate-distortion (R-D) cost. And we constrain the number of reference pictures for prediction unit (PU) performing motion estimation by using the motion information of the upper depth PU. The proposed methods reduce computational complexity of the HEVC encoder by constraining the maximum coding depth and the reference frame. We could achieve about 39% computational complexity reduction with marginal bitrate increase of 1.2% in the comparison with HM6.1 HEVC reference software.
Fast Prediction Unit Decision Using Quantized Transform Coefficient
Gweon, Ryeong-Hee ; Lee, Yung-Lyul ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 725~733
DOI : 10.5909/JBE.2012.17.5.725
MPEG and VCEG have constituted a collaboration team called JCT-VC(Joint Collaborative Team on Video Coding) and have been developing the HEVC(High Efficiency Video Coding) standard. The next generation video coding standard HEVC shows higher compression rate compared with the H.264/AVC standard, but the encoder computational complexity of the HEVC encoder is significantly high. In order to reduce this computational complexity in the HEVC encoder, a fast prediction unit decision is proposed. The proposed fast prediction unit decision method reduces the encoder complexity by skipping the remaining prediction units if the current prediction unit does not have any non-zero quantized transform coefficient. The proposed method reduces the encoder computational complexity by 50.3% comparing with HM6.0 but it maintains the same level of coding efficiency.
Secondary Residual Transform for Lossless Intra Coding in HEVC
Kwak, Jae-Hee ; Lee, Yung-Lyul ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 734~741
DOI : 10.5909/JBE.2012.17.5.734
A new lossless intra coding method based on residual transform is applied to the next generation video coding standard HEVC (High Efficiency Video Coding). HEVC includes a multi-directional spatial prediction method to reduce spatial redundancy by using neighboring samples as a prediction for the samples in a block of data to be encoded. In the new lossless intra coding method, the spatial prediction is performed as samplewise DPCM (Difference Pulse Code Modulation) but is implemented as block-based manner by using residual transform and secondary residual transform on the HEVC standard. Experimental results show that the new lossless intra coding method reduces the bit rate by approximately 6.45% in comparison with the lossless intra coding method previously included in the HEVC standard.
Parallel Method for HEVC Deblocking Filter based on Coding Unit Depth Information
Jo, Hyun-Ho ; Ryu, Eun-Kyung ; Nam, Jung-Hak ; Sim, Dong-Gyu ; Kim, Doo-Hyun ; Song, Joon-Ho ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 742~755
DOI : 10.5909/JBE.2012.17.5.742
In this paper, we propose a parallel deblocking algorithm to resolve workload imbalance when the deblocking filter of high efficiency video coding (HEVC) decoder is parallelized. In HEVC, the deblocking filter which is one of the in-loop filters conducts two-step filtering on vertical edges first and horizontal edges later. The deblocking filtering can be conducted with high-speed through data-level parallelism because there is no dependency between adjacent edges for deblocking filtering processes. However, workloads would be imbalanced among regions even though the same amount of data for each region is allocated, which causes performance loss of decoder parallelization. In this paper, we solve the problem for workload imbalance by predicting the complexity of deblocking filtering with coding unit (CU) depth information at a coding tree block (CTB) and by allocating the same amount of workload to each core. Experimental results show that the proposed method achieves average time saving (ATS) by 64.3%, compared to single core-based deblocking filtering and also achieves ATS by 6.7% on average and 13.5% on maximum, compared to the conventional uniform data-level parallelism.
Adaptive Intra Prediction Method using Modified Cubic-function and DCT-IF
Lee, Han-Sik ; Lee, Ju-Ock ; Moon, Joo-Hee ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 756~764
DOI : 10.5909/JBE.2012.17.5.756
In current HEVC, prediction pixels are finally calculated by linear-function interpolation on two reference pixels. It is hard to expect good performance on the case of occurring large difference between two reference pixels. This paper decides more accurate prediction pixel values than current HEVC using linear function. While existing prediction process only uses two reference pixels, proposed method uses DCT-IF. DCT-IF analyses frequency characteristics of more than two reference pixels in frequency domain. And proposed method calculates prediction value adaptively by using linear-function, DCT-IF and cubic-function to decide more accurate interpolation value than to only use linear function. Cubic-function has a steep slope than linear-function. So, using cubic-function is utilized on edge in prediction unit. The complexity of encoder and decoder in HM6.0 has increased 3% and 1%, respectively. BD-rate has decreased 0.4% in luma signal Y, 0.3% in chroma signal U and 0.3% in chroma signal V in average. Through this experiment, proposed adaptive intra prediction method using DCT-IF and cubic-function shows increased performance than HM6.0.
Complexity Reduction Method Using Inter-layer CU Depth Information for Scalable Video Coding Base on HEVC
Jang, Hyeong-Moon ; Nam, Jung-Hak ; Sim, Dong-Gyu ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 765~780
DOI : 10.5909/JBE.2012.17.5.765
In this paper, we propose a fast mode decision method that determines the coding unit depth for enhancement layers to improve an encoding speed of a scalable video encoder based on HEVC. To decide the coding unit depth of the enhancement layer, firstly, the coding unit depth of the corresponded coding unit in the basement layer is employed. At this stage, the final CU depth is decided by calculating the rate-distortion costs of one lower depth to one upper depth of the referenced depth. The proposed method can reduce a computational load since it does not calculate the rate-distortion costs for all the depths of a target CU. We found that the proposed algorithm decreases encoding complexity of 26% with approximately 1.4% bit increment, compared with the simulcast encoder of the HM 4.0.
A Prediction Cost based Complexity Reduction Method for Bi-Prediction in High Efficiency Video Coding (HEVC)
Kim, Jong-Ho ; Lee, Ha-Hyun ; Jun, Dong-San ; Cho, Suk-Hee ; Choi, Jin-Soo ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 781~788
DOI : 10.5909/JBE.2012.17.5.781
In HEVC, the fast search method is used for reducing the complexity of the motion prediction procedure. It is consisted of the sub-sampled SAD which reduce the complexity of Sum of Absolute Differences(SAD) calculation and the simplified bi-prediction method which reduce the iterations of the uni-prediction for the bi-prediction. The computational complexity is largely decreased by the fast search method but the coding gain is also decreased. In this paper, the simplified bi-prediction is extended to compensate the performance loss and the prediction cost based complexity reduction methods are also proposed to reduce the complexity burden by the extended bi-prediction method. A prediction cost based complexity reduction method is consisted of early termination method for the extended bi-prediction and the bi-prediction skipping method. Compare with HM 6.0 references S/W, the average 0.42% of BD-bitrate is decreased by both the extended bi-prediction method and the prediction cost based complexity reduction methods with negligible increasement of the complexity.
Disparity and Image Characteristics of Stereoscopic Video Affecting on Viewing Safety
Seo, Young-Ho ; Bae, Yun-Jin ; Kim, Woo-Youl ; Kim, Dong-Wook ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 789~807
DOI : 10.5909/JBE.2012.17.5.789
The purpose of this paper is to find various disparity factors in conjunction with situations and contexts of the contents that cause viewer`s discomfort, which is to make a content production guideline for viewer`s safety, eventually. As a methodology, we extract the experimental data by letting various viewers push a pre-defined key as long as they feel discomfort during watching stereo 3D contents. For each contents, we extract the disparities and disparity changes for the focal point, vicinity of the focal point (ROI, region of interest), and the whole image. For each contents, each point or part of contents is analyzed to find the factors causing discomfort with the two prepared data with watching the contents in 3D. Then, all the analyzed data are re-analyzed to find the strength of each factor. The results from the analyses are explained from the factors having relatively high strength first. It includes the factors that are not known as well as the ones that we can already guess.
Gabor Descriptors Extraction in the SURF Feature Point for Improvement Accuracy in Face Recognition
Lee, Jae-Yong ; Kim, Ji-Eun ; Oh, Seoung-Jun ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 808~816
DOI : 10.5909/JBE.2012.17.5.808
Face recognition has been actively studied and developed in various fields. In recent years, interest point extraction algorithms mainly used for object recognition were being applied to face recognition. The SURF(Speeded Up Robust Features) algorithm was used in this paper which was one of typical interest point extraction algorithms. Generally, the interest points extracted from human faces are less distinctive than the interest points extracted from objects due to the similar shapes of human faces. Thus, the accuracy of the face recognition using SURF tends to be low. In order to improve it, we propose a face recognition algorithm which performs interest point extraction by SURF and the Gabor wavelet transform to extract descriptors from the interest points. In the result, the proposed method shows around 23% better recognition accuracy than SURF-based conventional methods.
Robust Viewpoint Estimation Algorithm for Moving Parallax Barrier Mobile 3D Display
Kim, Gi-Seok ; Cho, Jae-Soo ; Um, Gi-Mun ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 817~826
DOI : 10.5909/JBE.2012.17.5.817
This paper presents a robust viewpoint estimation algorithm for Moving Parallax Barrier mobile 3D display in sudden illumination changes. We analyze the previous viewpoint estimation algorithm that consists of the Viola-Jones face detector and the feature tracking by the Optical-Flow. The sudden changes in illumination decreases the performance of the Optical-flow feature tracker. In order to solve the problem, we define a novel performance measure for the Optical-Flow tracker. The overall performance can be increased by the selective adoption of the Viola-Jones detector and the Optical-flow tracker depending on the performance measure. Various experimental results show the effectiveness of the proposed method.
Multichannel Audio Reproduction Technology based on 10.2ch for UHDTV
Lee, Tae-Jin ; Yoo, Jae-Hyoun ; Seo, Jeong-Il ; Kang, Kyeong-Ok ; Kim, Whan-Woo ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 827~837
DOI : 10.5909/JBE.2012.17.5.827
As broadcasting environments change rapidly to digital, user requirements for next-generation broadcasting service which surpass current HDTV service become bigger and bigger. The next-generation broadcasting service progress from 2D to 3D, from HD to UHD and from 5.1ch audio to more than 10ch audio for high quality realistic broadcasting service. In this paper, we propose 10.2ch based multichannel audio reproduction system for UHDTV. The 10.2ch-based audio reproduction system add two side loudspeakers to enhance the surround sound localization effect and add two height and one ceiling loudspeakers to enhance the elevation localization effect. To evaluate the proposed system, we used APM(Auditory Process Model) for objective localization test and conducted subjective localization test. As a result of objective/subjective localization test, the proposed system shows the statistically same performance compare with 22.2ch audio system and shows the significantly better performance compared with 5.1ch audio system.
Multi-view Image Generation from Stereoscopic Image Features and the Occlusion Region Extraction
Lee, Wang-Ro ; Ko, Min-Soo ; Um, Gi-Mun ; Cheong, Won-Sik ; Hur, Nam-Ho ; Yoo, Ji-Sang ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 838~850
DOI : 10.5909/JBE.2012.17.5.838
In this paper, we propose a novel algorithm that generates multi-view images by using various image features obtained from the given stereoscopic images. In the proposed algorithm, we first create an intensity gradient saliency map from the given stereo images. And then we calculate a block-based optical flow that represents the relative movement(disparity) of each block with certain size between left and right images. And we also obtain the disparities of feature points that are extracted by SIFT(scale-invariant We then create a disparity saliency map by combining these extracted disparity features. Disparity saliency map is refined through the occlusion detection and removal of false disparities. Thirdly, we extract straight line segments in order to minimize the distortion of straight lines during the image warping. Finally, we generate multi-view images by grid mesh-based image warping algorithm. Extracted image features are used as constraints during grid mesh-based image warping. The experimental results show that the proposed algorithm performs better than the conventional DIBR algorithm in terms of visual quality.
Color Improvement of Retinex Image Using the Maximum Color Difference Signal Table
Lee, Jae-Won ; Jung, Jee-Hoon ; Hong, Sung-Hoon ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 851~863
DOI : 10.5909/JBE.2012.17.5.851
Retinex algorithm enhances the contrast of image through visibility improvement. However, the conventional Retinex methods may produces color distortions due to error of hue representation and over-saturation since the methods work in RGB color space. In this paper, we propose a new Retinex algorithm with color correction, which improves contrast by using MSR(Multi-Scale Retinex) working in YCbCr color space and adaptively compensates the color saturation based on the maximum color difference table. Our algorithm maps the color difference signals to the correct gamut to prevent over-saturation phenomenon by considering the correlation between luminance and hue dependent saturation. Simulations results show that the proposed method gives better color improvement compared to the conventional methods.
Carrier Frequency Offset Estimation Method for Single-Carrier MIMO Systems
Oh, Jong-Kyu ; Kim, Joon-Tae ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 864~875
DOI : 10.5909/JBE.2012.17.5.864
In this paper, we propose a carrier frequency offset estimation method for single-carrier MIMO systems. In the proposed method, phase rotated PN (Pseudo-Noise) sequences are transmitted to prevent a cancelling out of partial PN sequences. After removing a modulation of received PN sequences by multiplying of complex conjugated PN Sequences which are locally generated in receiver, a CFO (Carrier Frequency Offset) is accurately estimated by employing L&R method which is a kind of ML (Maximum Likelihood) estimation algorithm and uses multiple auto-correlatos. In addition, the frequency offset estimation scheme by using channel state information is proposed for accurate CFO estimation in time-varying Rayleigh channel. By performing computer simulations, MSE (Mean Square Error) performance of proposed method is almost same as MSE performance of SISO systems in AWGN channel. Moreover, MSE Performance of proposed method with using channel information is higher than MSE performances of SISO system and conventional method in time-varying Rayleigh channel.
Performance Analysis of DVC Scheme with Adaptive Gray Code for Frame Difference Signal
Kim, Jin-Soo ; Kim, Jae-Gon ; Choi, Hae-Chul ;
Journal of Broadcast Engineering, volume 17, issue 5, 2012, Pages 876~890
DOI : 10.5909/JBE.2012.17.5.876
In this paper, we investigated the performances of the distributed video codec with adaptive Gray code to apply for frame-difference signal. That is, the best cases and the worst cases were analyzed and compared by considering the statistical characteristics of the frame difference signal in view of the Gray code allocation. Through computer simulations, if 9-bit data for frame difference signal is generated for luminance signal with 8-bit definition and so n-bit is allocated to the quantized coefficient, we were able to find the best method to reduce the virtual channel noise by adding
to the frame difference signal. Through computer simulation with test video sequences, it was shown that the performance difference between the best cases and the worst cases is larger than about 1.5dB at same rate. It is expected that the results in this paper are applicable for the transform-domain scheme as well as the pixel-domain scheme.