• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.2
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• pp.149-159
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• 2001

The conventional block-based motion prediction suffers, especially in low bit-rate video application, from shortcomings such as blocking artifacts of motion field and unstable motion estimation. To overcome the deficiency, this paper proposes one method of adopting a new motion compensation scheme based on the irregular triangular mesh structure while keeping the current block-based DCT coding structure of H.263 as much as possible. To represent the reconstructed previous frame using minimal number of control points, the proposed method designs content-adaptive irregular triangular meshes, and then, estimate the motion vector of each control point using the affine transformation-based matching. The predicted current frame is obtained by applying the affine transformation to each triangular mesh. Experiment with the several real video sequences shows improvement both in objective and subjective picture quality over the conventional block-based H.263 method.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1058-1068
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• 2011

Video FRUC (Frame Rate Up Conversion) is one of the main issues that have arisen in recent years with the explosive growth of video sources and display formats in consumer electronics. Most advanced FRUC algorithms adopt an efficient motion interpolation technique to determine the motion vector field of interpolated frames. But, in some application areas such as post processing in receiver side, it is necessary to evaluate how well the MCI (Motion Compensated Interpolation) frame was reconstructed. In order to achieve this aim, first, this paper introduces some cost functions to estimate the reliability of a block in the MCI frame. Then, by using these functions, this paper proposes two distortion estimation models for evaluating how much noise was produced in the MCI frame. Through computer simulations, it is shown that the proposed estimation methods perform effectively in estimating the noises of the MCI frame.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.661-666
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• 2004

In the wireless communication systems, transmission errors degrade the reconstructed image quality severely. Error concealment in video communication is becoming increasingly important because transmission errors can cause single or multiple loss of macroblocks in video delivery over unreliable channels such as wireless networks and internet. Among various techniques which can reduce the degradation of video quality, the error concealment techniques yield good performance without overheads and the modification of the encoder. In this paper, lost image blocks can be concealed with the OBMC(Overlapped Block Motion Compensation) after new motion vectors of the lost image blocks are allocated by median values using the adaptive selection with motion vectors of adjacent blocks. We know our algorithm is more effective in case of continuous GOB loss. The results show a significant improvement over the zero motion error concealment and other temporal concealment methods such as Motion Vector Rational Interpolation or Median＋OBMC by 3dB gain in PSNR.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.310-319
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• 2016

This paper proposes an effective FRUC (Frame Rate Up-Conversion) technique, which is based on ROI (Region Of Interest) separations and adaptive motion vector refinement. In this paper, in order to overcome the weakness of the EBME (Extended Bi-lateral Motion Estimation) algorithm, which is widely known in FRUC techniques, first, the proposed algorithm performs a bi-directional motion estimation for the complementary asymmetric region. Then, the proposed algorithm classifies each block into ROI or non-ROI block and refine motion vectors in accordance with their block characteristics to have a higher accuracy than the conventional EBME algorithm, specially, for the occlusion regions. The experimental results show that the proposed algorithm can improves 0.59dB on average PSNR as compared to the conventional method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.4 s.316
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• pp.51-59
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• 2007

In this paper, we propose an efficient hardware architecture for H.264/AVC CAVLC (Context-based Adaptive Variable Length Coding) decoding which used for baseline profile and extended profile. Previous CAVLC architectures are consisted of five step block and each block gets effective bits from Controller block and Accumulator. If large number of non-zero coefficients exist, process for getting effective bits has to iterates many times. In order to reduce this unnecessary process, we propose two techniques, which combine five steps into four steps and reduce process to get efficiency bit by skipping addition step. By adopting these two techniques, the required processing time was reduced about 26% compared with previous architectures. It was designed in a hardware description language and total logic gate count was 16.83k using 0.18um standard cell library.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.662-668
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• 2013

Mobile communication systems have been adopting link adaptive transmission schemes such as adaptive modulation and coding (AMC) and hybrid-ARQ (HARQ). Incremental redundancy (IR) HARQ scheme is known to be highly efficient in terms of throughput and power consumption and can be a good solution for mobile communication systems. In this paper, we propose an IR-HARQ scheme based on dual-diagonal parity-type block LDPC codes in which we define a transmission priority of coded bits and propose the sub-packet construction rule. We present the throughput performance of IR-HARQ with various modulation and coding and multi-antenna modes. Consequently, the proposed scheme provides the improvement of system throughput by elaborate link adaptation with CQI information.

• The KIPS Transactions:PartB
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• v.9B no.2
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• pp.199-204
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• 2002

Since motion estimation and motion compensation methods remove the redundant data to employ the temporal redundancy in images, it plays an important role in digital video compression. Because of its high computational complexity, however, it is difficult to apply to high-resolution applications in real time environments. If we have information about the motion of an image block before the motion estimation, the location of a better starting point for the search of an exact motion vector can be determined to expedite the searching process. In this paper, we present an adaptive motion estimation approach bated on temporal correlations of consecutive image frames that defines the search pattern and determines the location of the initial search point adaptively. Through experiments, compared with DS(Diamond Search) algorithm, the proposed algorithm is about 0.1∼0.5(dB) better than DS in terms of PSNR(Peak Signal to Noise Ratio) and improves as high as 50% compared with DS in terms of average number of search point per motion vector estimation.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.5
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• pp.55-63
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• 2011

This paper describes new moving target detection technique combining two algorithms to detect targets and reject clutters in video frame images for surveillance system: One obtains the region of moving target using phase correlation method using $N{\times}M$ sub-block images in frequency domain. The other uses adaptive threshold using learning weight for extracting target candidates in subtracted image. The block region with moving target can be obtained using the characteristics that the highest value of phase correlation depends on the movement of largest image in block. This technique can be used in camera motion environment calculating and compensating camera movement using FFT phase correlation between input video frame images. The experimental results show that the proposed algorithm accurately detects target(s) with a low false alarm rate in variety environment using the receiver operating characteristics (ROC) curve.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.8
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• pp.360-367
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• 2002

In this paper, genetic algorithm based adaptive image enhancement filtering scheme is proposed and Implemented on FPGA board. Conventional filtering methods require a priori noise information for image enhancement. In general, if a priori information of noise is not available, heuristic intuition or time consuming recursive calculations are required for image enhancement. Contrary to the conventional filtering methods, the proposed filter system can find optimal combination of filters as well as their sequent order and parameter values adaptively to unknown noise types using structured genetic algorithms. The proposed image enhancement filter system is mainly composed of two blocks. The first block consists of genetic algorithm part and fitness evaluation part. And the second block consists of four types of filters. The first block (genetic algorithms and fitness evaluation blocks) is implemented on host computer using C code, and the second block is implemented on re-configurabe FPGA board. For gray scale control, smoothing and deblurring, four types of filters(median filter, histogram equalization filter, local enhancement filter, and 2D FIR filter) are implemented on FPGA. For evaluation, three types of noises are used and experimental results show that the Proposed scheme can generate optimal set of filters adaptively without a pioi noise information.

• Journal of Broadcast Engineering
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• v.7 no.4
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• pp.317-326
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• 2002

The adaptive coding schemes in H.264 standardization provide a significant ceding efficiency and some additional features like error resilience and network friendliness. The variable block size motion compensation using multiple reference frames is one of the key H.264 coding elements to provide main performance gain, but also the main culprit that increases the overall computational complexity. For this reason, this paper proposes a selective motion estimation algorithm based on variable block size for fast motion estimation in H.264. After we find the SAD(Sum of Absolute Difference) at initial points using diamond search, we decide whether to perform additional motion search in each block. Simulation results show that the proposed method is five times faster than the conventional full search in case of search range $\pm$32.