• Title, Summary, Keyword: Discrete Cosine Transform

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Transform Domain Adaptive Filtering with a Chirp Discrete Cosine Transform LMS (CDCTLMS를 이용한 변환평면 적응 필터링)

  • Jeon, Chang-Ik;Yeo, Song-Phil;Chun, Kwang-Seok;Lee, Jin;Kim, Sung-Hwan
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.8
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    • pp.54-62
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    • 2000
  • Adaptive filtering method is one of signal processing area which is frequently used in the case of statistical characteristic change in time-varing situation. The performance of adaptive filter is usually evaluated with complexity of its structure, convergence speed and misadjustment. The structure of adaptive filter must be simple and its speed of adaptation must be fast for real-time implementation. In this paper, we propose chirp discrete cosine transform (CDCT), which has the characteristics of CZT (chrip z-transform) and DCT (discrete cosine transform), and then CDCTLMS (chirp discrete cosine transform LMS) using the above mentioned algorithm for the improvement of its speed of adaptation. Using loaming curve, we prove that the proposed method is superior to the conventional US (normalized LMS) algorithm and DCTLMS (discrete cosine transform LMS) algorithm. Also, we show the real application for the ultrasonic signal processing.

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CT Reconstruction using Discrete Cosine Transform with non-zero DC Components (영이 아닌 DC값을 가지는 Discrete Cosine Transform을 이용한 CT Reconstruction)

  • Park, Do-Young;Yoo, Hoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.7
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    • pp.1001-1007
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    • 2014
  • This paper proposes a method to reduce operation time using discrete cosine transform and to improve image quality by the DC gain correction. Conventional filtered back projection (FBP) filtering in the frequency domain using Fourier transform, but the filtering process uses complex number operations. To simplify the filtering process, we propose a filtering process using discrete cosine transform. In addition, the image quality of reconstructed images are improved by correcting DC gain of sinograms. To correct the DC gain, we propose to find an optimum DC weight is defined as the ratio of sinogram DC and optimum DC. Experimental results show that the proposed method gets better performance than the conventional method for phantom and clinical CT images.

Classification of ECG arrhythmia using Discrete Cosine Transform, Discrete Wavelet Transform and Neural Network (DCT, DWT와 신경망을 이용한 심전도 부정맥 분류)

  • Yoon, Seok-Joo;Kim, Gwang-Jun;Jang, Chang-Soo
    • 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%.

An Effective Encryption Algorithm for 3D Printing Model Based on Discrete Cosine Transform

  • Pham, Ngoc-Giao;Moon, Kwnag-Seok;Lee, Suk-Hwan;Kwon, Ki-Ryong
    • Journal of Korea Multimedia Society
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    • v.21 no.1
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    • pp.61-68
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    • 2018
  • In this paper, we present an effective encryption algorithm for 3D printing models in the frequency domain of discrete cosine transform to prevent illegal copying, access in the secured storage and transmission. Facet data of 3D printing model is extracted to construct a three by three matrix that is then transformed to the frequency domain of discrete cosine transform. The proposed algorithm is based on encrypting the DC coefficients of matrixes of facets in the frequency domain of discrete cosine transform in order 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 proposed algorithm is provide a better method and more security than previous methods.

Fast Detection of Forgery Image using Discrete Cosine Transform Four Step Search Algorithm

  • Shin, Yong-Dal;Cho, Yong-Suk
    • Journal of Korea Multimedia Society
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    • v.22 no.5
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    • pp.527-534
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    • 2019
  • Recently, Photo editing softwares such as digital cameras, Paintshop Pro, and Photoshop digital can create counterfeit images easily. Various techniques for detection of tamper images or forgery images have been proposed in the literature. A form of digital forgery is copy-move image forgery. Copy-move is one of the forgeries and is used wherever you need to cover a part of the image to add or remove information. Copy-move image forgery refers to copying a specific area of an image itself and pasting it into another area of the same image. The purpose of copy-move image forgery detection is to detect the same or very similar region image within the original image. In this paper, we proposed fast detection of forgery image using four step search based on discrete cosine transform and a four step search algorithm using discrete cosine transform (FSSDCT). The computational complexity of our algorithm reduced 34.23 % than conventional DCT three step search algorithm (DCTTSS).

Image Coding of Visually Weighted t Discrete Cosine Transform (시각 하중 이산여현변환 영상부호화)

  • 이문호;박주용
    • Journal of the Korean Professional Engineers Association
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    • v.22 no.2
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    • pp.19-25
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    • 1989
  • Utilizing a cosine transform in image compression has several recognized performance benefits, resulting in the ability to attain large compression ratio with small quality loss. Also, various models incorporating Human Visual System (HVS) to Discrete Cosine Trans-form (DCT) scheme are considered. Using the exact frequency components of DCT basis function, the optimum modulation transfer function (MTF) is obtained analytically. The errors at a block boundary which is important factor in transform coder are criteria for error measurement. The HVS weight coding results in perceptually higher quality images compared with the unweighted scheme.

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A New Algorithm for An Efficient Implementation of the MDCT/IMDCT (MDCT/IMDCT의 효율적인 구현을 위한 새로운 알고리즘)

  • 조양기;이원표;인치호;김희석
    • Proceedings of the IEEK Conference
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    • pp.2471-2474
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    • 2003
  • The modified discrete cosine transform (MDCT) and its inverse transform (IMDCT) are employed in subband/transform coding schemes as the analysis/synthesis filter bank based on time domain aliasing cancellation (TDAC). And they are the most computational intensive operations in layer III of the MPEG audio coding standard. In this paper, we propose a new efficient algorithm for the MDCT/IMDCT computation. It is based on the MDCT/IMDCT computation algorithm using the discrete cosine transforms (DCTs), and it employs two discrete cosine transform of type II(DCT-II) to compute the MDCT/IMDCT. In addition to, it takes advantage of ability in calculating the MDCT/IMDCT computation, where the length of a data block is divisible by 4. The proposed algorithm in this paper requires less calculation complexity than the existing methods. Also, it can be implemented by the parallel structure,, and its structure is particularly suitable for VLSI realization.

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WARPED DISCRETE COSINE TRANSFORM EXTENSION TO THE H.264/AVC

  • Lee, Sang-Heon;Cho, Nam-Ik
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.326-329
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    • 2009
  • This paper proposes a new video compression algorithm using an adaptive transform that is adjusted depending on the frequency contents of the input signals. The adaptive transform is based on the warped discrete cosine transform (WDCT) which is shown to provide better performance than the DCT at high bit rates, when applied to JPEG compression scheme [1, 2, 3]. The WDCT is applied to the video compression in this paper, as a new feature in the H.264/AVC. The proposed method shows the coding gain over the H.264/AVC at high bit rates. The coding gain is shown over the 35dB PSNR quality, and the gain increases as the bit rate increases. (about 1.0dB at 45dB PSNR quality at maximum)

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Alternative Transform Based on the Correlation of the Residual Signal (잔여 신호의 상관성에 기반한 선택 변환)

  • Lim, Sung-Chang;Kim, Dae-Yeon;Lee, Yung-Lyul
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.45 no.3
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    • pp.80-92
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    • 2008
  • Many predominant video coding tools in terms of coding efficiency were adopted in the latest video coding standard, H.264/AVC. Regardless of development of these predominant video coding tools such as the variable block-size motion estimation/compensation, intra prediction based on various directions, and so on, the discrete cosine transform has been continuously used starting from the early video coding standards. Generally, the correlation coefficient of the residual signal is usually less than 0.5 when this residual signal is actually encoded. In this interval of correlation coefficient, the discrete cosine transform does not show the optimal coding gain, and the discrete sine transform which is a sub-optimal transform when the correlation coefficient is in the interval from -0.5 to 0.5 can be used in conjunction with the discrete cosine transform in the video coding. In this paper, an alternative transform that alternatively uses the discrete sine transform and integer cosine transform in H.264/AVC by using rate-distortion optimization is proposed. The proposed method achieves a BD-PSNR gain of up to 0.71 dB compared to H.264/AVC JM 10.2 at relatively high bitrates.

Low delay window switching modified discrete cosine transform for speech and audio coder (음성 및 오디오 부호화기를 위한 저지연 윈도우 스위칭 modified discrete cosine transform)

  • Kim, Young-Joon;Lee, In-Sung
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.2
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    • pp.110-117
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    • 2018
  • In this paper, we propose a low delay window switching MDCT (Modified Discrete Cosine Transform) method for speech/audio coder. The window switching algorithm is used to reduce the degradation of sound quality in non-stationary trasient duration and to reduce the algorithm delay by using the low delay TDAC (Time Domain Aliasing Cancellation). While the conventional window switching algorithms uses overlap-add with different lengths, the proposed method uses the fixed overlap add length. It results the reduction of algorithm delay by half and 1 bit reduction in frame indication information by using 2 window types. We apply the proposed algorithm to G.729.1 based on MDCT in order to evaluate the performance. The propose method shows the reduction of algorithm delay by half while speech quality of the proposed method maintains same as the conventional method.