• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1880-1885
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• 1989

In this paper, a new approach for systolic array realizing the discrete cosine transform (DCT) based on discrete Fourier transform (DFT) of an input sequence is presented. The proposed array is based on a simple modified DFT(MDFT) version of the Goertzel algorithm combined with Kung's approach and is proved perfectly. This array requires N cells, one multiplier and takes N clock cycles to produce a complete N-point DCT and also is able to process a continuous stream of data sequences. We have analyzed the output signal-to-noise ratio(SNR) and designed the circuit level layout of one-PE chip. The array coefficients are static adn thus stored-product ROM's can be used in place of multipliers to limit cost as eliminate errors due to coefficients quantization.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.7
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• pp.851-858
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• 1988

In this paper, we propose two different VLSI architectures for the parallel computation of DCT (discrete cosine transform) algorithm. First, it is shown that the DCT algorithm can be implemented on the existing systolic architecture for the DFT(discrete fourier transform) by introducing some modification. Secondly, a new prime factor DCT algorithm based on the prime factor DFT algorithm is proposed. And it is shown that the proposed algorihtm can be implemented in parallel on the systolic architecture for the prime factor DFT. However, proposed algorithm is only applicable to the data length which can be decomposed into relatively prime and odd numbers. It is also found that the proposed systolic architecture requires less multipliers than the structures implementing FDCT(fast DCT) algorithms directly.

• Journal of Information Processing Systems
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• v.13 no.4
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• pp.852-862
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• 2017

In this work a Discrete Cosine Transform (DCT)-based feature dimensionality reduced approach for fingerprint matching is proposed. The DCT is applied on a small region around the core point of fingerprint image. The performance of our proposed method is evaluated on a small database of Bologna University and two large databases of FVC2000. A dimensionally reduced feature vector is formed using only approximately 19%, 7%, and 6% DCT coefficients for the three databases from Bologna University and FVC2000, respectively. We compared the results of our proposed method with the discrete wavelet transform (DWT) method, the rotated wavelet filters (RWFs) method, and a combination of DWT+RWF and DWT+(HL+LH) subbands of RWF. The proposed method reduces the false acceptance rate from approximately 18% to 4% on DB1 (Database of Bologna University), approximately 29% to 16% on DB2 (FVC2000), and approximately 26% to 17% on DB3 (FVC2000) over the DWT based feature extraction method.

• Journal of the Semiconductor & Display Technology
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• v.8 no.3
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• pp.45-50
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• 2009

Recently, block-based transforms, like discrete cosine transform (DCT), have been widely used in image and video coding standards, but block-based transforms have a weak point with blocking effect. However, the integer lapped orthogonal transform (ILOT) is a tool for block-based coding with bases functions that overlap near blocks, so it has a strong point against blocking effect. Although it has slightly higher arithmetic complexity than the DCT, the coding gain is significantly higher with much less blocking artifacts. This paper introduces the integer lapped orthogonal transforms and discrete cosine transform. And we compare the performance of DCT with ILOT which is proposed a new efficient method for image coding applications.

• Journal of Computing Science and Engineering
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• v.11 no.4
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• pp.152-159
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• 2017

Three-dimensional (3D) printing is applied to many areas of life, but 3D printing models are stolen by pirates and distributed without any permission from the original providers. Moreover, some special models and anti-weapon models in 3D printing must be secured from the unauthorized user. Therefore, 3D printing models must be encrypted before being stored and transmitted to ensure access and to prevent illegal copying. This paper presents a selective encryption algorithm for 3D printing models based on clustering and the frequency domain of discrete cosine transform. All facets are extracted from 3D printing model, divided into groups by the clustering algorithm, and all vertices of facets in each group are transformed to the frequency domain of a discrete cosine transform. The proposed algorithm is based on encrypting the selected coefficients in the frequency domain of discrete cosine transform to generate the encrypted 3D printing model. Experimental results verified that the proposed algorithm is very effective for 3D printing models. The entire 3D printing model is altered after the encryption process. The decrypting error is approximated to be zero. The proposed algorithm provides a better method and more security than previous methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.12
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• pp.5058-5072
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• 2015

Quaternions have been commonly employed in color image processing, but when the existing pure quaternion representation for color images is used in perceptual hashing, it would degrade the robustness performance since it is sensitive to image manipulations. To improve the robustness in color image perceptual hashing, in this paper a full quaternion representation for color images is proposed by introducing the local image luminance variances. Based on this new representation, a novel Full Quaternion Discrete Cosine Transform (FQDCT)-based hashing is proposed, in which the Quaternion Discrete Cosine Transform (QDCT) is applied to the pseudo-randomly selected regions of the novel full quaternion image to construct two feature matrices. A new hash value in binary is generated from these two matrices. Our experimental results have validated the robustness improvement brought by the proposed full quaternion representation and demonstrated that better performance can be achieved in the proposed FQDCT-based hashing than that in other notable quaternion-based hashing schemes in terms of robustness and discriminability.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.497-505
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• 2016

The two-dimensional (2D) Discrete Cosine Transform (DCT) is used widely in image and video processing systems. The perception of human visualization permits us to design approximate rather than exact DCT. In this paper, we propose a digital implementation of 16-point approximate 2D DCT architecture based on one-dimensional (1D) DCT and Modified Gate Diffusion Input (MGDI) technique. The 8-point 1D Approximate DCT architecture requires only 12 additions for realization in digital VLSI. Additions can be performed using the proposed 8 transistor (8T) MGDI Full Adder which reduces 2 transistors than the existing 10 transistor (10T) MGDI Full Adder. The Approximate MGDI 2D DCT using 8T MGDI Full adders is simulated in Tanner SPICE for $0.18{\mu}m$ CMOS process technology at 100MHZ.The simulation result shows that 13.9% of area and 15.08 % of power is reduced in the 8-point approximate 2D DCT, 10.63 % of area and 15.48% of power is reduced in case of 16-point approximate 2D DCT using 8 Transistor MGDI Full Adder than 10 Transistor MGDI Full Adder. The proposed architecture enhances results in terms of hardware complexity, regularity and modularity with a little compromise in accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.180-181
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• 2018

JPEG is a most widely used standard image compression technology. This research introduces the JPEG image compression algorithm and describes each step in the compression and decompression. Image compression is the application of data compression on digital images. The DCT (discrete cosine transform) is a technique for converting a time domain to a frequency domain. First, the image is divided into 8 by 8 pixel blocks. Second, working from top to bottom left to right, the DCT is applied to each block. Third, each block is compressed through quantization. Fourth, the array of compressed blocks that make up the image is stored in a greatly reduced amount of space. Finally if desired, the image is reconstructed through decompression, a process using IDCT (inverse discrete cosine transform).

• The KIPS Transactions:PartA
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• v.12A no.4 s.94
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• pp.313-320
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• 2005

The 2-D discrete cosine transform (DCT) is an integral part of video and image processing; it is used in both the PEG and MPEG enciding standards. As streaming video is brought to mobile devices, it becomes important that it is possible to calculate the DCT in an energy-efficient manner. In this paper, we present a new algorithm the DCT with a linear array PEs. This design is optimized for energy efficiency. We analyze the energy, area, and latency tradeoffs available with this design and then compare its energy dissipation, area, and latency to those of Xilinx's optimized IP core.

• The KIPS Transactions:PartB
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• v.9B no.5
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• pp.609-614
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• 2002

Watermarking is embedding a digital signal called as watermark into images to claim the ownership. In this paper, a new digital watermarking algorithm based on DCT (Discrete Cosine Transform) which enhances invisibility and robustness is proposed to improve contentional digital watermarking method using DCT. In the proposed method, it is possible to enhance invisibility and robustness using watermark reordering in which the relative significance of original DCT coefficients can be preserved in watermarked DCT coefficients, and the distortions of original DCT coefficients can be minimized. The experimental results show that the proposed method improves invisibility approximately 9～12[dB] and is more robust to various attacks than the conventional method.