• Journal of the Institute of Convergence Signal Processing
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• v.14 no.1
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• pp.13-20
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• 2013

A combined DWT and DCT based watermarking technique of low frequency watermarking with weighted correction is proposed. The DWT has excellent spatial localization, frequency spread and multi-resolution characteristics, which are similar to the theoretical models of the human visual system (HVS). The DCT based watermarking techniques offer compression while DWT based watermarking techniques offer scalability. These desirable properties are used in this combined watermarking technique. In the proposed method watermark bits are embedded in the low frequency band of each DCT block of selected DWT sub-band. The weighted correction is also used to improve the imperceptibility. The extracting procedure reverses the embedding operations without the reference of the original image. Compared with the similar approach by DCT based approach and DWT based approach, the experimental results show that the proposed algorithm apparently preserves superiori mage quality and robustness under various attacks such as JPEG compression, cropping, sharping, contrast adjustments and so on.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.597-600
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• 1999

TMN5 used to test the performance of H.263 is a DCT-based H.263 which DCT is used as transform coding, but DWT is used instead of DCT and adaptive quantizer of being appropriate to DWT is designed in this paper while the structure of TMN5 is maintained. DWT-based H.263, which is proposed in this paper, is excellent in transplantation of the existing system and can improve frame rate by transmitting more Frame. Also, the average PSNR, objective quality of image, has been lost at degree of average 0.35㏈ in luminance signals, but has been improved over a average of 2㏈ in chrominance signals. Subjective quality of image has been improved as blocking effect, which has seriously occurred in DCT based H.263, is diminished. DWT-based H.263 can. therefore. advance video quality of image comparing with the existing ways.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.340-342
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• 2012

Integral Imaging (II) is an attractive technique for three-dimensional (3D) image, video display and recording. Inherently, the high resolution II requires an enormous amount of data for storing and transmitting of 3D scenes. Compression techniques attempt to evade this issue. In this study, we made a comparative performance analysis of popular transforming/compression techniques such as the Discrete Cosine Transform (DCT) and the Discrete Wavelet Transform (DWT) in order to compress 3D-II. The standard baseline JPEG (Joint Photographic Experts Group) using DCT and JPEG 2000 using DWT methods were manipulated in our experiments. In our analysis, we have shown that the DWT based JPEG 2000 compression methodology could be a good alternative for 3D-II.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1C
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• pp.51-58
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• 2007

The purpose of this paper is to find an efficient encryption scheme for digital holograms (fringe patterns) with low encryption cost. Therefore, we introduced several encryption attempts in both hologram-domain and frequency-domain (both DCT-domain and DWT-domain) on the bases of the results from analyzing the properties of the coefficients in each domain. To effectively hide the image information, 25%, 1.5625%, and 0.0244% of the original fringe pattern need to be encrypted for hologram-domain scheme, DWT-domain scheme, and DCT-domain scheme, respectively. Consequently the DCT-domain scheme was the most efficient and it is caused by the fact that the ability for DCT to concentrate the energy of a given 2-dimensional image into a small area is the best. The encryption schemes and the analyses in this paper are expected to be used effectively on the researches on encryption and others for digital holograms.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.527-528
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• 2006

In this paper, we propose an IP design and implementation of System on a chip(SoC) for Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) processor using adder-based DA(Adder-based Distributed Arithmetic). To reduced hardware cost and to improve operating speed, the combined DCT/ DWT processor used the bit-serial method and DA module. The transform of coefficient equation result in reduction in hardware cost and has a regularity in implementation. We use Verilog-HDL and Xilinx ISE for simulation and implement FPGA on SoCMaster-3.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.730-732
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• 2005

최근 이미지 압축, 워터마킹 또는 스케일러블 비디오 코딩 분야에서 DCT와 DWT 연산을 선택적으로 사용하거나, 혼합하여 사용하는 경우가 늘어나고 있다. 이러한 두개의 연산을 사용하는 방법은 소프트웨어적인 프로그램을 사용하거나 하드웨어를 따로 구현하여 사용하였다. 본 연구에서는 하나의 모듈로 두개의 연산을 수행할 수 있는 재구성 하드웨어를 제안한다. 또한 DCT와 DWT연산에 있어서, 가장 많은 연산을 수행하는 부분은 계수(Coefficient)값과 입력 값의 내적 연산(Inner Product)을 수행하는 것인데, 이 내적연산을 하는데 있어서 곱셈기를 사용하지 않는 분산연산을 사용함으로써 연산의 복잡도를 줄이고, 하드웨어의 속도를 빠르게 하였다. 실험 환경은 Altera FPGA를 사용한 Excalibur_ARM (EPXA10F1020Cl) 보드를 이용하여 구현하였으며, 동작속도는 47.85MHz이다.

• 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 Institute of Electronics Engineers of Korea SP
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• v.45 no.4
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• pp.1-9
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• 2008

This paper presents a rapid watermarking algorithm based on DC image, which provides a resilience to geometric distortion. Our proposed scheme is based on $8{\times}8$ block DCT that is widely used in image/video compression techniques (e.g., JPEG and MPEG). In particular, a DC image is analyzed by DWT to embed a watermark. To overcome a quality degradation caused by a watermark insertion into DC components, we discern carefully the intensity and amount of watermark along the different subbands of DWT. Note that the proposed technique supports a high throughput for a real-time watermark insertion and extraction by relying on a partial decoding (i.e., DC components) on $8{\times}8$ block DCT domain. Experimental result shows that the proposed watermarking scheme significantly reduces computation time of 82% compared with existing DC component based algorithm and yet provides invariant properties against various attacks such as geometric distortion and JPEG compression, etc.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.1
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• pp.1-8
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• 2014

Digital watermarking techniques are attracting attention as a proper solution to protect copyright for multimedia data. This paper proposes a new audio watermarking method based on Discrete Cosine Transformation (DCT) and Discrete Wavelet Transformation (DWT) for copyright protection. In our proposed watermarking method, the original audio is transformed into DCT domain and divided into two parts. Synchronization code is applied on the signal in first part and 2 levels DWT domain is applied on the signal in second part. The absolute value of DWT coefficient is divided into arbitrary number of segments and calculates the energy of each segment and middle peak. Watermarks are then embedded into each middle peak. Watermarks are extracted by performing the inverse operation of watermark embedding process. Experimental results show that the hidden watermark data is robust to re-sampling, low-pass filtering, re-quantization, MP3 compression, cropping, echo addition, delay, and pitch shifting, amplitude change. Performance analysis of the proposed scheme shows low error probability rates.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.727-732
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• 2012

This paper presents an approach to classify normal and arrhythmia from the MIT-BIH Arrhythmia Database using Discrete Cosine Transform(DCT), Discrete Wavelet Transform(DWT) and neural network. In the first step, Discrete Cosine Transform is used to obtain the representative 15 coefficients for input features of neural network. In the second step, Discrete Wavelet Transform are used to extract maximum value, minimum value, mean value, variance, and standard deviation of detail coefficients. Neural network classifies normal and arrhythmia beats using 55 numbers of input features, and then the accuracy rate is 98.8%.