• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4467-4486
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• 2016

Discrete cosine transform (DCT) based JPEG standard significantly improves the coding efficiency of image compression, but it is unacceptable event in serious blocking artifacts at low bit rate and low efficiency of high-definition image. In the light of all phase digital filtering theory, this paper proposes a novel transform based on discrete sine transform (DST), which is called all phase discrete sine biorthogonal transform (APDSBT). Applying APDSBT to JPEG scheme, the blocking artifacts are reduced significantly. The reconstructed image of APDSBT-JPEG is better than that of DCT-JPEG in terms of objective quality and subjective effect. For improving the efficiency of JPEG coding, the structure of JPEG is analyzed. We analyze key factors in design and evaluation of JPEG compression on the massive parallel graphics processing units (GPUs) using the compute unified device architecture (CUDA) programming model. Experimental results show that the maximum speedup ratio of parallel algorithm of APDSBT-JPEG can reach more than 100 times with a very low version GPU. Some new parallel strategies are illustrated in this paper for improving the performance of parallel algorithm. With the optimal strategy, the efficiency can be improved over 10%.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.70-77
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• 1984

This paper represents a fast computational algorithm for the discrete sine transform defined by Kekre and Solanki. Techniques are developed to factor the discrete sine trans form matrix into M=log2 2N matrices, where the number(N) of sampled data points is a power of two. Each factorial matrix contains not more than two non-zero real elem tints in any row or column. As a result of this method, the exact a배orithm for the fast discrete sine transform is accomplished. The algorithm is illustiated by a signal flow graph, which may be readily translated to hardware or software implementation.

• ETRI Journal
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• v.39 no.5
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• pp.672-682
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• 2017

Video compression exploits statistical, spatial, and temporal redundancy, as well as transform and quantization. In particular, the transform in a frequency domain plays a major role in energy compaction of spatial domain data into frequency domain data. The high efficient video coding standard uses the type-II discrete cosine transform (DCT-II) and type-VII discrete sine transform (DST-VII) to improve the coding efficiency of residual data. However, the DST-VII is applied only to the Intra $4{\times}4$ residual block because it yields relatively small gains in the larger block than in the $4{\times}4$ block. In this study, after rearranging the data of the residual block, we apply the DST-VII to the inter-residual block to achieve coding gain. The rearrangement of the residual block data is similar to the arrangement of the basis vector with a the lowest frequency component of the DST-VII. Experimental results show that the proposed method reduces the luma-chroma (Cb+Cr) BD rates by approximately 0.23% to 0.22%, 0.44% to 0.58%, and 0.46% to 0.65% for the random access, low delay B, and low delay P configurations, respectively.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.100-108
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• 2023

In hybrid block-based video coding, transform coding converts spatial domain residual signals into frequency domain data and concentrates energy in a low frequency band to achieve a high compression efficiency in entropy coding. The state-of-the-art video coding standard, VVC(Versatile Video Coding), uses DCT-2(Discrete Cosine Transform type 2), DST-7(Discrete Sine Transform type 7), and DCT-8(Discrete Cosine Transform type 8) for primary transform. In this paper, considering that DCT-2, DST-7, and DCT-8 are all linear transformations, we propose an inverse transform that reduces the number of multiplications in the inverse transform by using the linearity of the linear transform. The proposed inverse transform method reduced encoding time and decoding time by an average 26%, 15% in AI and 4%, 10% in RA without the increase of bitrate compared to VTM-8.2.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.2
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• pp.103-110
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• 1996

In this paper, we propose a unified systolic array for the computation of the 2D discrete cosine transform/discrete sine transform/discrete hartley transform (DCT/DST/DHT). The unified systeolic array for the 2D DCT/DST/DHT is a generalization of the unified systolic array for the 1D DCT/DST/DHT. In order to calculate the 2D transform, we compute 1D transforms along the row, transpose them, and obtain 1D transforms along the column. When we compare the proposed systolic array with the conventional method, our architecture exhibits a lot of advantages in terms of latency, throughput, and the number of PE's. The simulation results using very high speed integrated circuit hardware description language (VHDL), international standard language for hardware description, show the functional validity of the proposed architecture.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.9
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• pp.4448-4466
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• 2018

In recent years, due to its high efficiency and better performance, the high efficiency video coding (HEVC) has become the most common compression standard in the field of video coding. In this paper, the framework of HEVC is deeply analyzed, and an improved HEVC video coding algorithm based on all phase biorthogonal transform (APBT) is proposed, where APBT is utilized to replace the discrete cosine transform (DCT) and discrete sine transform (DST) in original HEVC standard. Based on the relationship between APBT and DCT, the integer APBT is deduced. To further improve the coding performance, an optimal HEVC video coding algorithm based on hybrid APBT is proposed. The coding performance of the proposed HEVC coding algorithm is improved without increasing the complexity. Experimental results show that compared with HEVC standard algorithm, the improved HEVC video coding algorithm based on hybrid APBT can improve the coding performance of chrominance components by about 0.3%.

• Journal of Broadcast Engineering
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• v.22 no.3
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• pp.321-326
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• 2017

High Efficiency Video Coding (HEVC) adopted the Discrete Cosine Transform-II (DCT-II) based interpolation filter to improve coding efficiency in motion compensation and estimation. In HEVC, the interpolation filters based on the DCT-II are composed of 8-point for half-pixel and 7-point for 1/4-pixel and 3/4-pixel. In this paper, a DST-VII based interpolation filter is used improve motion compensation and estimation. The experimental results which applied the DST-VII interpolation filter are presented. They show the 0.45% of average bitrate reduction in Random Access configuration and 0.5% of average bitrate reduction in Low Delay B configuration, respectively.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.37-40
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• 2021

비디오 압축 시 변환(transform)은 예측을 통해 만들어진 공간 영역에서의 잔차신호를 주파수 영역으로 변환함으로써 낮은 주파수 대역으로 에너지를 이동시켜 비디오 압축에서 중요한 역할을 수행한다. VVC(Versatile Video Coding)에서는 DCT-II(Discrete Cosine Transform-II), DST-VII(Discrete Sine Transform-VII), DCTVIII(Discrete Cosine Transform-VIII)를 이용하여 잔차신호 변환을 수행한다. 본 논문에서는 DCT-II, DST-VII, DCT-VIII 가 모두 선형 변환(linear transform)이라는 점에서 착안하여 변환의 선형성을 이용하여 계산량을 감소시키는 역변환을 제안한다. 실험결과 변환 수행 시 약 12.7%의 시간이 감소되는 것을 확인하였다.

• Journal of Industrial Technology
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• v.14
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• pp.19-28
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• 1994

We can get a tridiagonal block Toeplitz linear system by the finite difference approximation of 2-D Poisson equation. To exploit the nice property of this linear equation, we transform the equation into a Lyapunov equation and apply DST (discrete sine transform) to get diagonal matrix based Lyapunov equation. DST can be performed using FFT, which enables high-speed computaion. All the computations are performed on an SIMD parallel computer, the MasPar MP-2 with 4,096 processing elements. In this paper, parallel algorithm, mapping method of the algorithm onto the MP-2, and timing results are presented.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.107-109
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• 2017

HEVC 표준은 정수 화소로 표현된 신호에 DCT-II 를 기반으로 하는 보간 필터를 사용하여 부화소 신호를 생성한다. 움직임 보상 및 예측의 성능 향상을 위해서 부화소 신호를 생성하는 방법을 이용한다. HEVC 표준은 부화소를 각각 1/4-화소 단위로 생성을 하며, 부화소를 생성하기 위해서 길이가 다른 각각의 DCT 보간 필터를 사용하고 있다. 1/2-화소를 생성하는 경우에는 필터의 길이가 8 인 DCT 기반 보간 필터를 사용하며, 1/4-화소와 3/4-화소의 경우에는 필터의 길이가 7 인 DCT 기반 보간 필터를 사용한다. 본 논문에서는 DST-VII을 기반으로 하는 보간 필터를 제안하여, CTU-Level 단위로 RDO 과정을 통해 최적화된 보간 필터를 선택하여 사용한다. 본 논문에서 제안하는 방법은 HEVC 표준보다 BD-rate 가 Low Delay B 와 Random Access configurations 에서 각각 0.6%와 0.6%의 성능 향상을 가져오며 Low Delay P configuration 에서 0.5%의 성능감소를 보인다.