• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.103-112
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• 2011

Motion estimation (ME) is regarded as an important component in a video encoding process, because it consumes a large computation complexity. H.264/AVC requires additional computation overheads for fractional search and interpolation. This causes a problem that computational complexity is increased. In Motion estimation, SATD(Sum of Transform Difference) has the characteristics of a parabolic based on the minimum point. In this paper, we propose new prediction algorithm to reduce search point in motion estimation by sub-pixel interpolation characteristics. The proposed algorithm reduces the time of encoding process by decreasing computational complexity. Experimental results show that the proposed method reduces 20% of the computation complexity of motion estimation, while the degradation in video quality is negligible.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.4
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• pp.548-555
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• 2022

This paper describes the hardware implementation of elliptic curve cryptography (ECC) used as a core operation in elliptic curve digital signature algorithm (ECDSA). The ECC processor supports eight operation modes (four point operations, four modular operations) on the NIST P-521 curve. In order to minimize computation complexity required for point scalar multiplication (PSM), the radix-4 Booth encoding scheme and modified Jacobian coordinate system were adopted, which was based on the complexity analysis for five PSM algorithms and four different coordinate systems. Modular multiplication was implemented using a modified 3-Way Toom-Cook multiplication and a modified fast reduction algorithm. The ECC processor was implemented on xczu7ev FPGA device to verify hardware operation. Hardware resources of 101,921 LUTs, 18,357 flip-flops and 101 DSP blocks were used, and it was evaluated that about 370 PSM operations per second were achieved at a maximum operation clock frequency of 45 MHz.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.969-972
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• 2016

In this paper, we propose an algorithm of angular mode selection for high-performance HEVC intra prediction. HEVC intra prediction is used to remove the spatial redundancy. Intra prediction has a total of 35 modes and block size of $64{\times}64$ to $4{\times}4$. Intra prediction has a high amount of calculation and operational time due to performing all 35 modes for each block size for the best cost. The angular mode algorithm proposed has a simple difference between pixels of the original image and the selected angular mode. A decision is made to select one angular mode plus planar mode and DC mode to perform the intra prediction and determine the mode with the best cost. In effect, only three modes are executed compared to the traditional 35 modes. Performance evaluation index used are BD-PSNR and BD-Bitrate. For the proposed algorithm, BD-PSNR results averagely increased by 0.035 and BD-Bitrate decreased by 0.623 relative to the HM-16.9 intra prediction. In addition, the encoding time is decreased by about 6.905%.

• The KIPS Transactions:PartB
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• v.10B no.2
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• pp.143-150
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• 2003

Error concealment plays an important role in combating transmission errors. Methods of error concealment which produce better quality are generally of higher complexity, thus making some of the more sophisticated algorithms is not suitable for real-time applications. In this paper, we develop temporal and spatial error resilient video encoding and data hiding approach to facilitate the error concealment at the decoder. Block interleaving scheme is introduced to isolate erroneous blocks caused by packet losses for spatial area of error resilience. For temporal area of error resilience, data hiding is applied to the transmission of parity bits to protect motion vectors. To do error concealment quickly, a set of edge features extracted from a block is embedded imperceptibly using data hiding into the host media and transmitted to decoder. If some part of the media data is damaged during transmission, the embedded features are used for concealment of lost data at decoder. This method decreases a complexity of error concealment by reducing the estimation process of lost data from neighbor blocks. The proposed data hiding method of parity bits and block features is not influence much to the complexity of standard encoder. Experimental results show that proposed method conceals properly and effectively burst errors occurred on transmission channel like Internet.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.6
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• pp.736-745
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• 2002

In network delivery of compressed video, packets may be lost if the channel is unreliable like Internet. Such losses tend to of cur in burst like continuous bit-stream error. In this paper, we propose an effective error-concealment approach to which an error resilient video encoding approach is applied against burst errors and which reduces a complexity of error concealment at the decoder using data hiding. To improve the performance of error concealment, a temporal and spatial error resilient video encoding approach at encoder is developed to be robust against burst errors. For spatial area of error concealment, block shuffling scheme is introduced to isolate erroneous blocks caused by packet losses. For temporal area of error concealment, we embed parity bits in content data for motion vectors between intra frames or continuous inter frames and recovery loss packet with it at decoder after transmission While error concealment is performed on error blocks of video data at decoder, it is computationally costly to interpolate error video block using neighboring information. So, in this paper, a set of feature are extracted at the encoder and embedded imperceptibly into the original media. If some part of the media data is damaged during transmission, the embedded features can be extracted and used for recovery of lost data with bi-direction interpolation. The use of data hiding leads to reduced complexity at the decoder. Experimental results suggest that our approach can achieve a reasonable quality for packet loss up to 30% over a wide range of video materials.

• The KIPS Transactions:PartB
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• v.19B no.2
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• pp.83-92
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• 2012

Multimedia contents can be copied and manipulated without quality degradation. Therefore, they are vulnerable to digital forgery and illegal distribution. In these days, with increasing the importance of multimedia security, various multimedia security techniques are studied. In this paper, we propose a content authentication algorithm based on reversible watermarking which supports JPEG compression commonly used for multimedia contents. After splitting image blocks, a specific authentication code for each block is extracted and embedded into the quantized coefficients on JPEG compression which are preserved against lossy processing. At a decoding process, the watermarked JPEG image is authenticated by extracting the embedded code and restored to have the original image quality. To evaluate the performance of the proposed algorithm, we analyzed image quality and compression ratio on various test images. The average PSNR value and compression ratio of the watermarked JPEG image were 33.13dB and 90.65%, respectively, whose difference with the standard JPEG compression were 2.44dB and 1.63%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.193-202
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• 2010

In this paper, we propose a fast algorithm that can reduce the complexity for inter mode decision of the H.264 encoder. The main idea consists of two techniques. The first one is the technique early terminating mode decision process. We focused on the skip and $16{\times}16$ mode because these modes occupies the largest portion in most of sequences. The second one is the technique skipping unnecessary $8{\times}8$ modes. The time consumption caused by the $8{\times}8$ mode is very considerable. Therefore if we can extract the unnecessary $8{\times}8$ mode calculation well, a large amount of time can be saved in total encoding process. The experimental results show that the proposed algorithm can achieve up to 43% speed up ratio with insignificant PSNR loss. The increase of total bits encoded is also not noticeable.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.4
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• pp.235-241
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• 2016

Compared to the former H.264 standard, the number of the prediction modes has highly increased in HEVC intra prediction. Compression efficiency and accurate prediction are significantly improved. However, the computational complexity increases as well. To solve this problem, this paper proposes the new scheme where not only prediction modes but also block partition candidate are early chosen. Compared to the original intra prediction in HEVC, the proposed scheme achieves about 38% reduction in processing cycles with a marginal loss in compression efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1046-1051
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• 1999

It is well known that Parallel Concatenated Convolutional Codes(turbo codes) has a good performance for long block sizes. This thesis has analyzed the performance of turbo code which is based on voice or control frames with short frame sizes in the future mobile communication system. Also, at the similar decoding complexity, the performance of turbo code and convolutional codes in the speech/control frames, and the applicability of this system are considered. As a result, turbo code in short frame sizes present the performance of a BER of $10^{-3}$ or more over 3 iterations in the future mobile communication system. However, at a BER of $10^{-3}$ , if the same complexity is considered, the performance of rate 1/2 turbo code with K = 5 is better than that of convolutional code with K = 9 at low $E_b/N_0$, and the performance of turbo code with K = 3 is superior to that of convolutional code with K = 7. Rate 1/3 turbo code with K = 3 and 5 have similar to performance of rate 1/2 turbo code.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.639-646
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• 2006

Data compression technologies enable us to store and transfer large amount of data efficiently, and become more and more important due to increasing data size and the network traffic. Moreover, as a result of the increase of computing power, volumetric data produced from various applied science and engineering fields has been getting much larger. In this Paper, we present a volume compression scheme which exploits Daubeches wavelet transform. The proposed scheme basically supports lossy compression for 3D volume data, and provides unit-wise random accessibility. Since our scheme shows far lower error rates than the previous compression methods based on Haar filter, it could be used well for interactive visualization applications as well as large volume data compression requiring image fidelity.