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1
Abedi, Safdar Ali Syed. "Exploring Discrete Cosine Transform for Multi-resolution Analysis." Digital Archive @ GSU, 2005. http://digitalarchive.gsu.edu/cs_theses/12.
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Multi-resolution analysis has been a very popular technique in the recent years. Wavelets have been used extensively to perform multi resolution image expansion and analysis. DCT, however, has been used to compress image but not for multi resolution image analysis. This thesis is an attempt to explore the possibilities of using DCT for multi-resolution image analysis. Naive implementation of block DCT for multi-resolution expansion has many difficulties that lead to signal distortion. One of the main causes of distortion is the blocking artifacts that appear when reconstructing images transformed by DCT. The new algorithm is based on line DCT which eliminates the need for block processing. The line DCT is one dimensional array based on cascading the image rows and columns in one transform operation. Several images have been used to test the algorithm at various resolution levels. The reconstruction mean square error rate is used as an indication to the success of the method. The proposed algorithm has also been tested against the traditional block DCT.
2
Muller, Rikus. "Applying the MDCT to image compression." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1197.
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Thesis (DSc (Mathematical Sciences. Applied Mathematics))--University of Stellenbosch, 2009.The replacement of the standard discrete cosine transform (DCT) of JPEG with the windowed modifed DCT (MDCT) is investigated to determine whether improvements in numerical quality can be achieved. To this end, we employ an existing algorithm for optimal quantisation, for which we also propose improvements. This involves the modelling and prediction of quantisation tables to initialise the algorithm, a strategy that is also thoroughly tested. Furthermore, the effects of various window functions on the coding results are investigated, and we find that improved quality can indeed be achieved by modifying JPEG in this fashion.
3
Yu, Sungwook. "VLSI implementation of multidimensional discrete Fourier transform and discrete cosine transform /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Hu, Ta-Hsiang. "Discrete cosine transform implementation in VHDL." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA245791.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 1990.Thesis Advisor(s): Lee, Chin-Hwa ; Yang, Chyan. "December 1990." Description based on title screen as viewed on March 29, 2010. DTIC Identifier(s): Fast Fourier Transform, High Level Languages, CHIPS (Electronics), Computerized Simulation, Signal Processing, Theses, Algorithms, Floating Point Operation, VHDL (Vhsic Hardware Description Language). Author(s) subject terms: FFT System, DCT System Implementation. Includes bibliographical references (p. 152). Also available in print.
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Jin, Chengzhou. "Discrete Cosine Transform for Pre-coded EGPRS." Thesis, KTH, Signalbehandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98761.
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Due to the rapid growth of wireless multimedia service, new features such as improved spectral efficiency, latency and increased peak throughput are standardized in the current GSM/EDGE system. Higher order modulations and symbol rates are defined in Enhanced General Packet Radio Service phase 2 (EGPRS2) to achieve better throughput. However, the computational complexity in the traditional receiver can be very high when increased modulation orders are applied; additionally, the system becomes more sensitive to the impairments at an increased symbol rate. It is therefore desirable to have a less complex and more robust demodulator. Recently, a new study item which introduces the multi-carrier technique was proposed in the 3rd Generation Partnership Project (3GPP) standardization. Based on the channel partitioning using the Discrete Fourier Transform (DFT), a simple equalizer can be used, which greatly reduces the computational complexity on receiver, meanwhile achieves good throughput and robustness against impairments. In this thesis, another channel partitioning method by means of the Discrete Cosine Transform (DCT) is studied. Transmitter and receiver algorithms are developed, including a pre-filter designed at the receiver to facilitate the channel diagonalization. The link level performance is evaluated by means of simulations, under different test scenarios. The system’s robustness against impairments and peak-to-average ratio (PAR) reduction are also evaluated, and compared with a system based on the DFT pre-coding. From the simulations, the conclusions can be drawn that in this implementation, the DFT precoded EGPRS2 outperforms the DCT pre-coded EGPRS2 in all scenarios. The DCT pre-coded system also shows worse robustness against impairments and higher peak-to-average ratio reduction loss in throughput. The impact of pre-filter design on the DCT pre-coded system has also been analyzed, and it shows that there is a tradeoff between achieving good symmetrization, and preserving channel information in the frequency domain.
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Haque, S. M. Rafizul. "Singular Value Decomposition and Discrete Cosine Transform based Image Watermarking." Thesis, Blekinge Tekniska Högskola, Avdelningen för för interaktion och systemdesign, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5269.
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Rapid evolution of digital technology has improved the ease of access to digital information enabling reliable, faster and efficient storage, transfer and processing of digital data. It also leads to the consequence of making the illegal production and redistribution of digital media easy and undetectable. Hence, the risk of copyright violation of multimedia data has increased due to the enormous growth of computer networks that provides fast and error free transmission of any unauthorized duplicate and possibly manipulated copy of multimedia information. One possible solution may be to embed a secondary signal or pattern into the image that is not perceivable and is mixed so well with the original digital data that it is inseparable and remains unaffected against any kind of multimedia signal processing. This embedded secondary information is digital watermark which is, in general, a visible or invisible identification code that may contain some information about the intended recipient, the lawful owner or author of the original data, its copyright etc. in the form of textual data or image. In order to be effective for copyright protection, digital watermark must be robust which are difficult to remove from the object in which they are embedded despite a variety of possible attacks. Several types of watermarking algorithms have been developed so far each of which has its own advantages and limitations. Among these, recently Singular Value Decomposition (SVD) based watermarking algorithms have attracted researchers due to its simplicity and some attractive mathematical properties of SVD. Here a number of pure and hybrid SVD based watermarking schemes have been investigated and finally a RST invariant modified SVD and Discrete Cosine Transform (DCT) based algorithm has been developed. A preprocessing step before the watermark extraction has been proposed which makes the algorithm resilient to geometric attack i.e. RST attack. Performance of this watermarking scheme has been analyzed by evaluating the robustness of the algorithm against geometric attack including rotation, scaling, translation (RST) and some other attacks. Experimental results have been compared with existing algorithm which seems to be promising.Phone number: +88041730212
7
Chua, Doi-eng, and 蔡岱榮. "Some variations on Discrete-Cosine-Transform-based lossy image compression." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31222523.
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Deng, An-Te. "VHDL behavioral description of Discrete Cosine Transform in image compression." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28641.
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Hantehzadeh, Neda. "3-D Face Recognition using the Discrete Cosine Transform (DCT)." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1964658571&sid=3&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Bhardwaj, Divya Anshu. "Inverse Discrete Cosine Transform by Bit Parallel Implementation and Power Comparision." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2447.
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The goal of this project was to implement and compare Invere Discrete Cosine Transform using three methods i.e. by bit parallel, digit serial and bit serial. This application describes a one dimensional Discrete Cosine Transform by bit prallel method and has been implemented by 0.35 ìm technology. When implementing a design, there are several considerations like word length etc. were taken into account. The code was implemented using WHDL and some of the calculations were done in MATLAB. The VHDL code was the synthesized using Design Analyzer of Synopsis; power was calculated and the results were compared.
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Shah, Rajul R. (Rajul Ramesh) 1979. "Hardware implementation of a low-power two-dimensional discrete cosine transform." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16859.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 143-144).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
In this project, a JPEG compliant, low-power dedicated, two-dimensional, Discrete Cosine Transform (DCT) core meeting all IBM Softcore requirements is developed. Power is optimized completely at the algorithmic, architectural, and logic levels. The architecture uses row-column decomposition of a fast 1-D algorithm implemented with distributed arithmetic. It features clock gating schemes as well as power-aware schemes that utilize input correlations to dynamically scale down power consumption. This is done by eliminating glitching in the ROM Accumulate (RAC) units to effectively stop unnecessary computation. The core is approximately 180K transistors, runs at a maximum of 100MHz, is synthesized to a .18[mu]m double-well CMOS technology with a 1.8V power supply, and consumes between 63 and 87 mW of power at 100MHz depending on the image data. The thesis explores the algorithmic evaluations, architectural design, development of the C and VHDL models, verification methods, synthesis operations, static timing analysis, design for test compliance, power analysis, and performance comparisons for the development of the core. The work has been completed in the ASIC Digital Cores I department of the IBM Microelectronics Division in Burlington, Vermont as part of the third assignment in the MIT VI-A program.
by Rajul R. Shah.
M.Eng.
12
Scargall, Lee David. "Very low bit-rate digital video coding." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299046.
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Mclean, Ivan Hugh. "An adaptive discrete cosine transform coding scheme for digital x-ray images." Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1002032.
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The ongoing development of storage devices and technologies for medical image management has led to a growth in the digital archiving of these images. The characteristics of medical x-rays are examined, and a number of digital coding methods are considered. An investigation of several fast cosine transform algorithms is carried out. An adaptive cosine transform coding technique is implemented which produces good quality images using bit rates lower than 0.38 bits per picture element
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Banham, Benjamin E. "An Evolutionary Approach to Image Compression in the Discrete Cosine Transform Domain." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/5.
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This paper examines the application of genetic programming to image compression while working in the frequency domain. Several methods utilized by JPEG encoding are applied to the image before utilizing a genetic programming system. Specifically, the discrete cosine transform (DCT) is applied to the original image, followed by the zig-zag scanning of DCT coefficients. The genetic programming system is finally applied to the one-dimensional array resulting from the zig-zag scan. The research takes an existing genetic programming system developed for the spatial domain and develops DCT domain functionality. The results from the DCT domain-based genetic programming system are compared with those from the spatial domain-based system, and show improvements to the image quality with a reduction up to half of the evolved image's average error. The results show that working in the frequency domain has advantages over the spatial domain. Several methods to exploit these advantages are proposed and evaluated.
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Murali, Swetha. "Design of Assistive Human-Machine-Interface control signal classifiers using the Discrete Cosine Transform." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674094141&sid=8&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Lin, Chen-Chieh, and 林成頡. "A Unified Architecture Design of Recursive Discrete Fourier Transform and Inverse Modified Discrete Cosine Transform." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/53681842824278817088.
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碩士國立成功大學
電機工程學系碩博士班
97
The thesis presents a novel unified architecture of the recursive Discrete Fourier Transform (DFT) and the Inverse Modified Cosine Transform (IMDCT) algorithms. The proposed design is supporting multi-formats and multi-length frames, such as MP3, AAC, AAC in DRM, AC3, VQ, Ogg (N=12, 36, 64, 128, 240, 256, 512, 1024, 1920, 2048, 4096 and 8192 points) of IMDCT and DFT in DRM (N=288, 256, 176, 112 points). In order to implement the unified architecture, the kernel of the proposed design is adpoted the recursive DFT algorithm. Due to the limit of speed of the recursive DFT architecture, we used 2-D algorithm to improve this problem. Trandicitonally, the coefficients are implemented by lookup table, but the method will cost large chip area. Thus, we use a memory-free algorithm to solve this problem. The proposed design not only reduces amounts of the coefficients greatly but also supports the multi-format for various audio codecs, if it is built in a media platform. For those of implementation, the proposed architecture only costs five multipliers. The cycle counts of the proposed architecture are 242 times improvement, and then the proposed design are lower than other existing literature of the recursive architecture. TSMC 0.18μm CMOS 1P6M technology is used to implement the proposed design. The chip can be operated at the frequency of 25MHz, the core size iii is 2 0.94�e0.99mm , and the power consummation is 22.97mW. Therefore, it is more suitable for multi-format of audio codecs.
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Yao, Shu-Nung, and 姚書農. "A Low-Cost Modified Discrete Cosine Transform Architecture for MPEG AAC." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/30510247881909048281.
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碩士國立成功大學
電機工程學系碩博士班
95
Most of current audio coding standards use the modified discrete cosine transform (MDCT) to transform an audio sequence from time domain to frequency domain. This thesis presents a low-cost MDCT architecture based on Maclaurin series. Most architectures used lookup table to approach trigonometric function, but the lookup table in MPEG AAC will cause the design large and inflexible. Therefore, we adopt Maclaurin series to design the computation circuit and apply the symmetry and periodic identities of trigonometric function to reduce the circuit complexity. It results that our proposed architecture can be implemented with less area than other MDCT architectures. 0.18 μm TSMC cell library technology is used to synthesize the architecture. The proposed architecture takes about 6040 gates with maximum operation frequency of 58.8 MHz. Therefore, it is suitable for low-cost multimedia applications.
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Tsung-Ming, Lo, and 羅聰明. "The Implementation of Modified Discrete Cosine Transform via Permuted Difference Coefficient." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/65758856736582188678.
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碩士大同工學院
電機工程研究所
86
This thesis is devoted to the implementations of the modified discrete cosine transform (MDCT).Using the permuted difference coefficient (PDC) method, fewer multipliers is needed only. In additional, one of the important intrinsic properties, the same magnitudes of the absolute value of basis vector's elements in each row within the MDCTs coefficient matrix, makes the proposed permuted difference coefficient structure (PDCS) are all identical for the computationof each coefficient, i.e., they have the equivalent process stages. This new architecture ownsthe advantages of high structural regularity, high speed, and high accuracy. Above all, the proposed architecture has shown its performance for lengh-N=8, 256 and 512 MDCT with the simulation of finite word-length. Two of the main quantization error in this architecture, round-off error of original coefficients and input sequences, are also illustrated in the simulation. It is shown that the round-off error of coefficients is less sensitive than that of inputs. These results in that the representation of the original coefficient in the shorter word length is able to reduce the number of stages of the PDC structure, even to obtain the high signal-to-noise ratio (SNR).
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Tsai, Sheng-Yuan, and 蔡聖源. "FPGA Implementation of modified 2-D Discrete Cosine Transforms." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/74303204802939890101.
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碩士國立高雄第一科技大學
電腦與通訊工程所
90
The two dimensional discrete cosine transform (2D-DCT) is widely used in digital signal processing, particularly for digital image processing in high speed transmission. There are two classes to realize in hardware structure, including the direct method, and the indirect method which is also called row-column method. It is more efficient for using the direct method. However, due to the computational complexity, the row-column method still has been adopted in the hardware implementation. In the indirect method, one dimensional of the rows or columns DCT coefficient are computed in advance. Then, a transpose matrix is obtained, and the elements of the transpose matrix are saved in a transpose matrix register. By the pivoting the elements of rows and columns, the one dimensional DCT of the transpose matrix is computed again. From performing twice one dimensional DCT transformations, then a two dimensional DCT has been formulated. The processing steps of one dimensional DCT are as follows: (1)Transform the DCT matrix into two 4*4 matrix. Then, change the elements of non-input data to 1’s complements. There 1’s complements have special weight individually. (2)Eight coefficient matrices. Based on these eight coefficient matrices have been obtained by above processing step. The partial products of all DCT coefficient can be found out. In the implementation of the circuit, only 26 adders are needed. (3)From this partial products, by means of adder_shift or 4-2 compressor tree circuit, we sum up all partial products by individual can be gained weight. Thus one dimensional DCT coefficients can be obtained. Compare the architecture of this method with New Distributed Arithmetic Architecture technique(NEDA) structure published in 2000. Our adder s of 1D DCT needed can be reduced from 35 to 26 in the same bit rate. If the hardware is designed in pipelined processing, the speed will be more promoted. The delay time is only equal to the delay of 4-2 compressor tree and an adder.
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Chen, Che-Hong, and 陳奇宏. "Efficient Recursive Structures for Forward and Inverse Modified Discrete Cosine Transforms." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/70164365153808374242.
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碩士國立成功大學
電機工程學系
88
The MP3 audio format uses the MPEG-1 audio Layer 3, which is one of the most advanced MPEG (Moving Picture Experts Group) standards for digital audio compression. The MPEG-1 audio Layer 3 has been widely used in internet and wireless communication and storage applications. The modified discrete cosine transform (MDCT) and its inverse transform (IMDCT) are the most complex operations in the MPEG-1 Layer 3 audio coding standard. In this thesis, we propose the new recursive structures for computing MDCT and IMDCT. This recursive structure is based on finite impulse response filters (IIR). We can use several IIR structures for concurrent computing MDCT and IMDCT components. The advantages of the proposed recursive IIR structure are rapid computational efficiency and high throughput rate. With regularity and modularity, the proposed recursive MDCT and IMDCT figured is suitable for VLSI implementation. In this thesis, we also realize a VLSI chip, which can perform both of the efficient recursion algorithms by using COMPASS 0.35µm high performance cell library with TSMC SPQM 0.35µm process technology. The realized VLSI takes about 7.5k gates in 2mm 2mm silicon area. The measurement result shows that the chip can work at about 50MHz clock rate.
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Hsu, Yu-Hsin, and 徐友信. "A New Fast Algorithm for Computing the Forward and Inverse Modified Discrete Cosine Transforms." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/82446174628541698698.
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碩士國立交通大學
電機與控制工程系
89
In this thesis, we present two new algorithms for computing the inverse modified discrete cosine transform(IMDCT) such that the computation complexity is equal to but the numerical performance is better than existing fast algorithms. To compute N-point IMDCT, the first algorithm is realized in the following sequence: multiplication of the N/2 input data by an N/2-value cosine sequence, N/2-point fast DCT, and a simple recursive addition. The second algorithm, closely reversing the computation procedures of the first algorithm, is realized in order by simple recursive addition, N/2-point IDCT, and multiplication of the IDCT output by an N/2-value cosine sequence. MDCT realization can be simply obtained by transposing the signal flow graph for evaluating the IMDCT. For the proposed two IMDCT algorithms, we have analyzed the realization complexity and simulated the fixed-point error. Comparing with the existing fast IMDCT algorithms in literature, we observe from the analysis and simulation results that the new algorithms have better numerical accuracy and thus can be realized with short word length, resulting in more efficient realization.
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Suresh, K. "MDCT Domain Enhancements For Audio Processing." Thesis, 2010. https://etd.iisc.ac.in/handle/2005/1184.
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Modified discrete cosine transform (MDCT) derived from DCT IV has emerged as the most suitable choice for transform domain audio coding applications due to its time domain alias cancellation property and de-correlation capability. In the present research work, we focus on MDCT domain analysis of audio signals for compression and other applications. We have derived algorithms for linear filtering in DCT IV and DST IV domains for symmetric and non-symmetric filter impulse responses. These results are also extended to MDCT and MDST domains which have the special property of time domain alias cancellation. We also derive filtering algorithms for the DCT II and DCT III domains. Comparison with other methods in the literature shows that, the new algorithm developed is computationally MAC efficient. These results are useful for MDCT domain audio processing such as reverb synthesis, without having to reconstruct the time domain signal and then perform the necessary filtering operations.
In audio coding, the psychoacoustic model plays a crucial role and is used to estimate the masking thresholds for adaptive bit-allocation. Transparent quality audio coding is possible if the quantization noise is kept below the masking threshold for each frame. In the existing methods, the masking threshold is calculated using the DFT of the signal frame separately for MDCT domain adaptive quantization. We have extended the spectral integration based psychoacoustic model proposed for sinusoidal modeling of audio signals to the MDCT domain. This has been possible because of the detailed analysis of the relation between DFT and MDCT; we interpret the MDCT coefficients as co-sinusoids and then apply the sinusoidal masking model. The validity of the masking threshold so derived is verified through listening tests as well as objective measures.
Parametric coding techniques are used for low bit rate encoding of multi-channel audio such as 5.1 format surround audio. In these techniques, the surround channels are synthesized at the receiver using the analysis parameters of the parametric model. We develop algorithms for MDCT domain analysis and synthesis of reverberation. Integrating these ideas, a parametric audio coder is developed in the MDCT domain. For the parameter estimation, we use a novel analysis by synthesis scheme in the MDCT domain which results in better modeling of the spatial audio. The resulting parametric stereo coder is able to synthesize acceptable quality stereo audio from the mono audio channel and a side information of approximately 11 kbps. Further, an experimental audio coder is developed in the MDCT domain incorporating the new psychoacoustic model and the parametric model.
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Suresh, K. "MDCT Domain Enhancements For Audio Processing." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1184.
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Modified discrete cosine transform (MDCT) derived from DCT IV has emerged as the most suitable choice for transform domain audio coding applications due to its time domain alias cancellation property and de-correlation capability. In the present research work, we focus on MDCT domain analysis of audio signals for compression and other applications. We have derived algorithms for linear filtering in DCT IV and DST IV domains for symmetric and non-symmetric filter impulse responses. These results are also extended to MDCT and MDST domains which have the special property of time domain alias cancellation. We also derive filtering algorithms for the DCT II and DCT III domains. Comparison with other methods in the literature shows that, the new algorithm developed is computationally MAC efficient. These results are useful for MDCT domain audio processing such as reverb synthesis, without having to reconstruct the time domain signal and then perform the necessary filtering operations.
In audio coding, the psychoacoustic model plays a crucial role and is used to estimate the masking thresholds for adaptive bit-allocation. Transparent quality audio coding is possible if the quantization noise is kept below the masking threshold for each frame. In the existing methods, the masking threshold is calculated using the DFT of the signal frame separately for MDCT domain adaptive quantization. We have extended the spectral integration based psychoacoustic model proposed for sinusoidal modeling of audio signals to the MDCT domain. This has been possible because of the detailed analysis of the relation between DFT and MDCT; we interpret the MDCT coefficients as co-sinusoids and then apply the sinusoidal masking model. The validity of the masking threshold so derived is verified through listening tests as well as objective measures.
Parametric coding techniques are used for low bit rate encoding of multi-channel audio such as 5.1 format surround audio. In these techniques, the surround channels are synthesized at the receiver using the analysis parameters of the parametric model. We develop algorithms for MDCT domain analysis and synthesis of reverberation. Integrating these ideas, a parametric audio coder is developed in the MDCT domain. For the parameter estimation, we use a novel analysis by synthesis scheme in the MDCT domain which results in better modeling of the spatial audio. The resulting parametric stereo coder is able to synthesize acceptable quality stereo audio from the mono audio channel and a side information of approximately 11 kbps. Further, an experimental audio coder is developed in the MDCT domain incorporating the new psychoacoustic model and the parametric model.
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Tsai, Hsing-Juan, and 蔡幸娟. "A Parameterizable Architecture for Two-Dimensional Discrete Cosine Transform and Inverse Discrete Cosine Transform." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/66341916946119230484.
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碩士逢甲大學
資訊工程所
93
The Discrete Cosine Transform (DCT) and Inverse Discrete Cosine Transforms (IDCT) are widely used in various audio and image processing applications. Because of the computation complexity of these algorithms, the dedicated hardware is usually required to achieve the performance of real-time applications. This thesis presents an efficient implementation of a two-dimensional DCT/IDCT processor using a serial-parallel systolic array architecture. The data transfer between processing elements is propagated serially in order to reduce the data communication cost. The data within the processing element is computed in a parallel manner to make the architecture high-speed. By carefully collocating the propagate data in the register of processing element, the transposition operation can be eliminated in this architecture. The block size of 2-D DCT/IDCT and the bit-width of computation data are extracted as parameters that can easily and systematically be adapted to conform to the various imaging coding standard. The behavior and structure model in C language is used to verify the correctness of the 2-D DCT/IDCT computation and the parameterizable implementation. The precision analysis of the 2-D DCT/IDCT implementation was performed by MatLab. The DCT design cost about 14K gate counts when block size is 8 and bit width is 6. The numbers of gate count increase 4 times when block size increases 2 times and those increase about 1.5 times when bit width increases 2 times.
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Das, Swastik, and Rasmi Ranjan Sethy. "Image Compression using Discrete Cosine Transform & Discrete Wavelet Transform." Thesis, 2009. http://ethesis.nitrkl.ac.in/1119/1/Image_Compression_using_DCT_%26_DWT.pdf.
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Image Compression addresses the problem of reducing the amount of data required to represent the digital image. Compression is achieved by the removal of one or more of
three basic data redundancies: (1) Coding redundancy, which is present when less than optimal (i.e. the smallest length) code words are used; (2) Interpixel redundancy, which results from correlations between the pixels of an image & (3) psycho visual redundancy which is due to data that is ignored by the human visual system (i.e. visually
nonessential information). Huffman codes contain the smallest possible number of code symbols (e.g., bits) per source symbol (e.g., grey level value) subject to the constraint that the source symbols are coded one at a time. So, Huffman coding when combined with technique of reducing the image redundancies using Discrete Cosine Transform (DCT)
helps in compressing the image data to a very good extent.
The Discrete Cosine Transform (DCT) is an example of transform coding. The current JPEG standard uses the DCT as its basis. The DC relocates the highest energies to the upper left corner of the image. The lesser energy or information is relocated into other areas. The DCT is fast. It can be quickly calculated and is best for images with smooth edges like photos with human subjects. The DCT coefficients are all real numbers unlike the Fourier
Transform. The Inverse Discrete Cosine Transform (IDCT) can be used to retrieve the image from its transform representation. The Discrete wavelet transform (DWT) has gained widespread acceptance in signal processing and image compression. Because of their inherent multi-resolution nature, wavelet-coding schemes are especially suitable for applications where scalability and tolerable degradation are important. Recently the JPEG committee has released its new image coding standard, JPEG-2000, which has been based upon DWT.
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Bhawna, Gauatm. "Image compression using discrete cosine transform and discrete wavelet transform." Thesis, 2010. http://ethesis.nitrkl.ac.in/1731/1/project.pdf.
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It is used specially for the compression of images where tolerable degradation is required. With the wide use of computers and consequently need for large scale storage and transmission of data, efficient ways of storing of data have become necessary. With the growth of technology and entrance into the Digital Age ,the world has found itself amid a vast amount of information. Dealing with such enormous information can often present difficulties. Image compression is minimizing the size in bytes of a graphics file without degrading the quality of the image to an unacceptable level. The reduction in file size allows more images to be stored in a given amount of disk or memory space. It also reduces the time required for images to be sent over the Internet or downloaded from Web pages.JPEG and JPEG 2000 are two important techniques used for image compression. JPEG image compression standard use DCT (DISCRETE COSINE TRANSFORM). The discrete cosine transform is a fast transform. It is a widely used and robust method for image compression. It has excellent compaction for highly correlated data.DCT has fixed basis images DCT gives good compromise between information packing ability and computational complexity. JPEG 2000 image compression standard makes use of DWT (DISCRETE WAVELET TRANSFORM). DWT can be used to reduce the image size without losing much of the resolutions computed and values less than a pre-specified threshold are discarded. Thus it reduces the amount of memory required to represent given image.
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Hwang, Jen-Jyh, and 黃仁志. "Digital Watermarking by Discrete Cosine Transform." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/99105407359663155102.
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碩士世新大學
資訊管理學研究所(含碩專班)
98
With the rapid development and extensive use of multimedia and network technology, multimedia protection such as image, audio, video is an urgent issue. It has been widely concerned to view watermarking technology as a powerful tool for copyright protection and safety certification. The paper is based on watermarks hiding creation by Discrete Cosine Transform (DCT) to analyze the robustness of the watermarked images. By not affecting the visually indistinguishable, this research hopes to provide bigger help for the area of watermarks hiding and digital documents.
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Chen, Chingson, and 陳慶勳. "Design and Implementation of Discrete Cosine Transform." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/38242894398568802620.
Full textAbstract:
碩士國立交通大學
電子研究所
83
Discrete Cosine Transform (DCT) is now used in many communication standards for the removal of redundancies of correlation in random sequences. A random sequence with less correlation could be well compressed after quantisation and entropy coding. Since DCT and its inverse (IDCT) cost much computation power, the design of DCT or IDCT is important in overall system consideration. Traditionally, ROM-Based Distributed Arithmetic (DA) architecture has been used in many commercial systems. Since ROMs cost much area in ROM-Based DA, a new architecture named Adder-Based DA replacing ROMs with serial adders is proposed in this thesis. This new architecture cost much less area than traditionally ROM-Based DA since the ROMs are all replaced by small serial adders. An IDCT chip with 16 mm^2 core area by CCL CMOS standard cells is designed and implemented in this thesis and speed of 98 M pels/ sec is achieved in simulation of VERILOG.
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Liu, Chun-Wen, and 劉仲文. "Adaptive Voltage Scaling for Discrete Cosine Transform." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/00937421266683497648.
Full textAbstract:
碩士國立交通大學
電子工程系所
96
In the modern digital IC system, adaptive voltage scaling is the most efficient technology for low power design. A new variable voltage generator (VVG) has been proposed in this paper. Five voltage levels ranged from 0.8V to 1.2V can be generated. An adaptive voltage scaling controller has been developed to fit the VVG to form an adaptive voltage scaling control system. In stead of the off-chip DC-DC converter which is often used in voltage regulation, the on-chip VVG takes an important roll in this system. Discrete Cosine Transform (DCT) has become one of the widely used transform techniques in digital signal processing. The adaptive voltage scaling system has been applied to DCT and reduces at most 45% power consumption of DCT. All simulations are implemented in TSMC0.13-μm CMOS technology.
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Tsai, Ya-Ting, and 蔡雅婷. "Object Detection with Integer Discrete Cosine Transform." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/40998194573150464909.
Full textAbstract:
碩士中華大學
資訊工程學系碩士班
100
Multimedia technologies, including those for video- and image-related applications, are widely used in various fields, such as security surveillance, medical diagnosis, education, entertainment, and business presentations. Moving objects are of significant interest in surveillance applications. Therefore, detecting the moving objects and identifying their moving trajectories may provide useful information for assuring the security of the monitored site. However, many lighting conditions cause video cameras to record the shadows of moving objects in video images. To identify accurate moving trajectories, the shadows associated with moving objects need to be removed from the recorded video images. Otherwise, false alarm may be triggered, or miscalculation may result. In this thesis, we propose a real-time method for verifying a block belonging to a moving object block or a shadow block. The method includes the following phases. First, we simplify the DCT transformation to construct a novel integer DCT transformation. Second, based on the integer DCT transformed DC and AC coefficients, the background variations are modeled via the GMM probabilistic models. Third, by analyzing the respective variances of the DC and the AC coefficients we can determine the foreground as a moving object or a shadow region. Experimental results show that our method outperforms the conventional methods in terms of accuracy and efficiency.
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Chung, Ming-Shen, and 鐘明聲. "FPGA Implementation of the Discrete Fourier Transform (DFT) and the Discrete Cosine Transform (DCT)." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/01456280849939764692.
Full textAbstract:
碩士國立高雄第一科技大學
電腦與通訊工程所
90
The Discrete Fourier Transform（DFT）has been widely applied in communcation, speech processing, image processing, radar and sonar systems, etc. The architecture of DFT implement can be classified into two fields：（1）one is a pipelined systolic architecture,（2）the other is a memory-based architecture. Discrete Cosine Transform（DCT）has been commonly adopted in the various atandardsfor image compression while FPGA has become a new trend of ASIC design, so we will apply FPGA techinque to implement the DFT and the DCT. This thesis deals with how to use FPGA techinque to implement： （1）the pipelined systolic array architecture that requires log2N complex multipliers, 2log2N complex adders, 2log2N multiplexers, N delay elements and is able to provide a throughput of one transform sample per clock cycle; （2）the memory-based architecture that consists of three two-port RAM’s, one ROM, one complex multiplier, two complex adders, one multiplexer, and has capability of computing one transform sample every log2N+1 clock cycles on average; （3）Improved architecture in（2）under increasing little hardware that spends half of run time, i.e.N(log2N)/2; （4）2D-DFT that use architecture in（2）of 1D-DFT; （5）DCT operation and 2D-DCT operation.
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Poplin, Dwight. "Distributed arithmetic architecture for the discrete cosine transform." Thesis, 1997. http://hdl.handle.net/1957/34243.
Full textAbstract:
The Discrete Cosine Transform is used in many image and video compression
standards. Many methods have been developed for efficiently computing the Discrete
Cosine Transform including flowgraph algorithms, distributed arithmetic and
two-dimensional decompositions.
A new architecture based on distributed arithmetic is presented for computing
the Discrete Cosine Transform and it's inverse. The main objective of the design is
to minimize the area of the VLSI implementation while maintaining the throughput
necessary for video and image compression standards such as MPEG and JPEG.
Several improvements have been made compared to previously published distributed
arithmetic architectures. These include elimination of four lookup tables and implementation
of the lookup tables using logic instead of ROM.
A model of the proposed architecture was written in C. The model was used to
verify the accuracy of the architecture and to do JPEG compression on a series of
test images. Behavioral simulations were performed with a hardware model written
in the Verilog hardware description language. These behavioral simulations verify
that the hardware implementation matches the C model. The model was synthesized
using the Synopsis synthesis tool. The gate count and clock rate of the design were
estimated using the synthesis results.Graduation date: 1997
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Liu, Jian-Cheng, and 劉建成. "Multi-dimentional Discrete Cosine Transform (DCT) Chip Design." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/56071432152209136424.
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Huang, Mu-Chang, and 黃牧常. "3D Face Recognition Using Discrete Cosine Transform Approach." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/67021825468958961692.
Full textAbstract:
碩士義守大學
電機工程學系
92
It is found that the feature extraction is important in recognition systems, such as faces recognition systems. This thesis studies a 3D face recognition system using the height information in the 3D face as the features. The 3D face database is built up by our 3D reconstruction system. The difference between 3D faces and 2D faces is that the variable in a 3D face including height information rather than the grey level in a 2D face image. The well known Discrete Cosine Transform and Principle Components Analysis method express very good performance in the image compression and faces recognition respectively. In this thesis, we propose the approach which combines DCT and PCA in forming face characteristic coefficient extraction, and compare the results with that using PCA and Wavelet Transform in the 3D face and the 2D face recognition. Our experimental results shows that the combined DCT and PCA approach has outstanding performance. The Nearest Feature Line, Linear Discriminant Analysis and Euclidean Distance are also incorporated into the process to improve the stability and robustness in the recognition system.
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LIN, RUI-QI, and 林瑞琦. "A study of discrete cosine and hartley transform." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/63434531522833015784.
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Shan, Yi-Chia, and 單益嘉. "ASYNCHRONOUS TWO-DIMENSION DISCRETE COSINE TRANSFORM CIRCUIT DESIGN." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/92076365087289606386.
Full textAbstract:
碩士大同大學
通訊工程研究所
96
This thesis proposes an asynchronous two-dimension discrete cosine transform (2-D DCT) processor. In asynchronous design, we used Sutherland’s Micropipelines to implement handshake pipeline. In DCT process, we adopt row-column decomposition method to separate 2-D DCT into two one-dimensional discrete cosine transform (1-D DCT) and a transpose memory. In order to realize the matrix calculation easily, multiplier and accumulator method has been adapted. We implement 2-D DCT function with Field Programable Gate Array (FPGA), and verify the design by the function simulation and timing simulation. FPGA has the programble property, so it’s very convient to be used in design level. We design asynchronous circuit which is based on FPGA architecture. The proposed circuit has asynchronous design spirit, but not completely followed the asynchronous design of the reference paper. The timing simulation result of 2-D DCT is not satisfied, the reason is related with FPGA architecture and the compile tool. Because we can not control the placement and routing of the circuit very well, the programs are auto compiled by FPGA tool, so it could cause the circuit failed. Although we met many challenges in FPGA design, but these experiences can be refered in the future ASIC asynchronous design.
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Lao, Hsing-Sheng, and 勞杏生. "Two-Dimension Interpolation Scheme Using Discrete Cosine Transform." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/10377114762758902394.
Full textAbstract:
碩士大同大學
通訊工程研究所
92
The interpolation of an image provides an approach to sample an image at a low rate for transmission or storage and then increase the sampling rate later. Some basic properties of an interpolator must satisfy these zero crossings guarantee that the image is not modified if it is resampled on the same grid. In addition to, the complexity of the interpolation algorithm is needed to be considered. Based on the above principles, a DCT (Discrete Cosine Transform) is proposed to do two-dimensional interpolation. We compare the results of using DCT with those of conventional using DFT (Discrete Fourie Transform) interpolation scheme and Wang’s DFT interpolation scheme. The experiment results show that no matter with human subjective perception to observe or with PSNR（Peak Signal - to - Noise Ratio）error metrics to measure, the results of two-dimensional DCT interpolation scheme are better than those of two-dimensional conventional DFT interpolation scheme and there is no big difference between the methods of two-dimensional DCT interpolation and Wang’s improved two-dimensional DFT interpolation scheme. And the complexity of the two-dimensional DCT interpolation algorithm is simpler than that of two-dimensional DFT one.
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Lin, You-Chung, and 林友中. "Design and Test of Discrete Cosine Transform Circuits." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/24801626295131883922.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
91
We present three testable 2-D Discrete Cosine Transform (DCT) circuits with high fault coverage and short test application time. The three DCT circuits are implemented with the row-column decomposition method, the direct method, and the folded direct method, respectively. We do some modifications when designing these DCT circuits to improve their fault coverage. These modifications include scan design, ad hoc design, and pipeline design, which are used according to different circumstances of these DCT circuits. After the modifications on these circuits, their fault coverage can reach 100% or near 100%. However, inserting scan design and pipeline design into the circuits would substantially increase the test application time. To overcome this defect, we apply two testing methods, namely the input reduction testing method and the broadcasting scan method, to these circuits. With these methods the test application time can be reduced to 0.647%~15.48% of those of the original circuits with single full scan design, and the area overhead is 5.84%~9.16% of those of the original circuits.
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Zheng, Rui Huang, and 鄭瑞煌. "Design and analysis of inverse discrete cosine transform." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/56157583926065706078.
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ZHENG, BO-WEN, and 鄭博文. "Design of three dimension discrete cosine transform coder." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/86282721872260597212.
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LIN, GUO-ZHEN, and 林國楨. "VLSI implementation of 2-dimensional discrete cosine transform." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/86587200420273634574.
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Wu, Yung-Gi, and 吳永基. "Finite State Discrete Cosine Transform for Image Compression." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/68322478679918275389.
Full textAbstract:
碩士國立成功大學
電機工程研究所
82
In this thesis,a new image compression method is devised. Discrete Cosine Transform is the kernel of the compressor. The new technique classifies the image subblock into eights classes by their characteristics which can be got from the transfomed domain.Four edge classes,three texture classes ,one smooth class.This kind of classification is called Three Model Classification.As to the overhead of classification ,finite state concept is used to reduce the overhead by predicting the current block's class from the previously blocks. In order to promote the correct ratio of prediction,edge orientation should be considered.We exploit the relationship between the transformed domain and edge orientation.As we know, the smooth regions occupy most part of a natual images.Larger coding size can get higher compression ratio in the smooth regions. But this will sacrifice the quality of complicated regions.In order to solve this deficiency.We devised a variable block coding size algorithm.The edge blocks use the fixed 8*8 block to keep the detailed parts and the variable block size segmentation scheme is applied to texture and smooth regions. The new segmentation method is called "class driven segmentation" The overhead of the segmention is zero. The simulation results show good quality for the decoded images.
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Hsieh, Yen-Long, and 謝顏隆. "Architecture Design of H.264 Discrete Cosine Transform." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/74024470056539167481.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
97
This thesis proposes a Discrete Cosine Transform architecture with high throughput and low area. This architecture can be applied in H.264 High Definition (HD) resolution video products. In H.264, the block sizes of the Discrete Cosine Transform are 4×4 and 8×8. The 8×8 block size transform is mainly used in Standard Definition resolution, High Definition resolution, and above Definition resolution. This thesis implements an 8×8 transform architecture. For application in HD resolution video products, the proposed architecture supplies enough high throughput, but a big area should also be associated with a high throughput. Through some property of the DCT, this thesis shows that the area can be reduced and then a high throughput and small area architecture can be implemented. In the proposed architecture, the specification of proposed architecture is 1080p and 60 frames per second. The proposed architecture is synthesized with TSMC 0.18 μm technology cell library and the operating speed is 81 MHz. In this operation speed, the proposed architecture has smaller area when compared with other architectures which also implement H.264 8×8 DCT architecture recently.
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Anshuman, Gaurav Jaiswal, and Ankit Rai. "Image compression using discrete cosine transform and wavelet transform and performance comparison." Thesis, 2007. http://ethesis.nitrkl.ac.in/4203/1/%E2%80%9CImage_compression_using_discrete_cosine.pdf.
Full textAbstract:
Image compression deals with reducing the size of image which is performed with the help of transforms. In this project we have taken the Input image and applied wavelet techniques for image compression and have compared the result with the popular DCT image compression. WT provided better result as far as properties like RMS error, image intensity and execution time is concerned. Now a days wavelet theory based technique has emerged in different
signal and image processing application including speech, image processing and computer vision. In particular Wavelet Transform is of interest for the analysis of non-stationary signals. In the WT at high frequencies short windows and at low frequencies long windows are used. Since discrete wavelet is essentially sub band–coding system, sub band coders have been quit successful in speech and image compression. It is clear that DWT has potential application in compression problem.
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Wu, Yung-Gi, and 吳永基. "New Image Compression Algorithms Based on Discrete Cosine Transform." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/98511424272795876877.
Full textAbstract:
博士國立成功大學
電機工程學系
88
Due to the progress of multimedia technologies, the demands of various types of information from users become huge so as to lead to the shortage of transmission bandwidth and storage space. The technologies of network and storage devices have been improving as well; however, the users'' desires always exceed the provided services currently. Therefore, data must be compressed before transmission or storage to achieve the needed quality under the circumstance of limited bandwidth. Among all kinds of media, video and image data occupy immense volume. Thus, the compression technologies of them have been intensively exploited in academy and industry. Discrete Cosine Transform (DCT) is an efficient and effective compression tool, which compacts the spatial energy into few coefficients in frequency domain. In addition, there are many fast algorithms for hardware realizations to speed up processing time. DCT has been employed in the compressions of image, video and speech, etc. In this dissertation, new algorithms based on DCT are developed to raise the compression performance of nature and medical images. The first part in this dissertation concentrates on the exploration of compression dimension (size). Here, a 2x2 block based DCT is proposed to compress image. It has the advantage of fast implementation and the compression ratio achieved by our method is better than other block based coding schemes. In addition, a 3D-DCT coder is proposed by us. It can not only attain very high compression ratio but also decrease blocky phenomena. The second part is to explore the processing of DCT coefficients. Conventional block based coding schemes do not consider the correlation among inter-blocks. Proposed spectral analysis strategy takes the correlation into account so as to raise the compression ratio significantly. Another new method is a sampling algorithm used to record the significant DCT coefficients and discard insignificant coefficients. Simulation demonstrates that proposed method is better than conventional coefficient processing method. Finally, a hybridization-coding scheme that combines DCT and Vector Quantization (VQ) is proposed in the last part of this dissertation. DCT is a post processing of VQ. It can decrease 50% bit rate compared to conventional VQ scheme.
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Cheng, Wen-Chu, and 鄭文珠. "A Robust Watermarking Method on Discrete Cosine Transform Domain." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/07301667868891898797.
Full textAbstract:
碩士國立清華大學
資訊工程學系
87
A novel image watermarking method with desired picture quality is proposed in this thesis. As usual, the watermark information is a long sequence of random values of normal distribution with zero mean and unity variance. The embedding process operates on the DCT domain as well as the spatial domain regarding the promotion of robustness and invisibility together. First, we understand that the quantity of embedding information is limited by the quantity of the corresponding DCT coefficient, especially for the low quantity coefficient the capability of robustness is declining. Conversely, it can sustain large quantity of information with pleasing level of robustness no matter how the postprocessing is done. Accordingly, our watermarking method adopts multiple and adaptive scaling factors to effectively embed the watermarking information with larger capacity relative to the other methods can do. These scaling factors are guided by desired image quality also. Besides, we superimpose a JND visual model on our method in spatial domain to guarantee the invisibility of watermarks. Furthermore, after the destructive postprocessing such as cropping or resizing, the current similarity measurement is useless. We propose an interesting similarity measurement that can truthfully reflect the similarity using the partial set of watermarks we only have. Finally, we conducted several experiments to justify the proposed method. The simulation results show that it surely prevent the original quality and against the JPEG compressing, cropping and resizing.
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Wu, Dong-yang, and 吳東洋. "STUDY OF RESIZING IMAGE BY USING DISCRETE COSINE TRANSFORM." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3c2835.
Full textAbstract:
碩士大同大學
通訊工程研究所
102
The interpolation is be widely used by digital image process, e.g. Polynomial Interpolation, DFT with zero-padding, etc. The polynomial interpolation increase accuracy at the cost of increasing computation complexity. In frequency domain, the DFT with zero-padding induces inaccurate estimates for edge of image. Discrete Cosine Transform Type-II (DCT-II) is popularly used in digital image process and signal process. Now, some successful literatures use the DCT-II with zero-padding to resize image, but it has an important defect. When the magnification factor is even, the original data would change. The original image data is the important reference, and therefore the current method is not applicable when the magnification is even. As current DCT-II interpolation method has this flaw, so our team revised the procedure of DCT-II interpolation a. It can guarantee the original value will not change when the magnification factor is even. This thesis tries to use the proposed DCT-II interpolation for resizing image with reduction of the computation complexity to improves well known defect. Compared with previous methods, the method used in this thesis can ensure that the most important original data value will not change no matter the magnification factor is odd or even, In addition artificial block edge can be removed by operation of sub-block. The proposed approach can achieve lower the operation time of the processing, and obtain better image quality.
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Tseng, Chao-Hsuing, and 曾昭雄. "Designs of Discrete Cosine Transform for Advanced Video Coding." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/60264778611132717506.
Full textAbstract:
博士國立成功大學
電機工程學系碩博士班
94
In the dissertation, we proposed several fast discrete cosine transform algorithms and integer transforms to reduce the computational complexity and achieve better energy compaction of video coders. First, the fast two-dimensional discrete cosine transform (DCT) and inverse discrete cosine transform (IDCT) algorithms were proposed to reduce computational complexity with regular and modular architecture. Then, a systematic design procedure of integer discrete cosine transforms (integer DCTs) and integer orthogonal discrete cosine transforms (IODCTs) was proposed to achieve better energy compaction and improve video coder performance. Finally, an enhanced rate-distortion cost function was proposed to improve the coding performance for H.264/AVC intra mode decision. The detailed discussions are addressed in the following: The proposed fast DCT and IDCT algorithms by using the direct computation approach are based on regular quad-matrix process. Since the algorithms through decomposition and reconstruction procedures can be repeatedly performed, we can easily extend them for the higher-dimension DCT and IDCT computations. With regularized procedures, all the heavy computations can be realized by the same computational kernel, which demands three multiplications and eight additions for each kernel. With high regular architecture and low computational complexity, the proposed algorithms after feasibility design show their advantages in both software and hardware implementation. The integer transform without drifting problems has been widely investigated. Among these researches, the integer transforms in various versions of H.264/AVC are the most attractive. We proposed a systematic design procedure of integer discrete cosine transforms (integer DCTs) and integer orthogonal discrete cosine transforms (IODCTs). Based on the proposed methods, we can design optimal integer transforms with better compaction ability and less computational complexity. With recursive design method, we can get many IODCTs and their reduced computations. The IODCTs depend on selections of normalization factors and cosine kernel integers. We use the compaction coding gain as the criterion to verify the performance of energy compaction to select a proper discrete transform. We found the famous integer transforms which achieve good approximations of the original DCT suggested in H.264/AVC coder all belong to IODCTs. Simulations show that the proposed IODCTs achieve better energy compaction and coding performances than the original DCT and integer transforms in H.264 coder. With advantages of computational efficiency and energy compaction, we believe that the proposed IODCTs could be efficiently and effectively used in advanced video coding systems. In H.264 advanced video coding (AVC) standard, the intra prediction plays an important role in compression of intraframes by referring surrounding coded blocks. It is obvious that either the SAD or SATD criterion suggested in the reference software will cause the worse coding performance compare to RD-optimized criterion. We first propose an enhanced cost function for intra 4x4 mode decision in H.264/AVC and then develop fast computation algorithms of the SATD and the SAITD to reduce the computation by using the property of linear transform and fixed spatial relation of predicted pixels in each intra mode. Simulation results show that when we adopt the enhanced cost function to select the best mode, the coding performance is better than the SAD (or SATD) criterion and is very similar to the RD optimized criterion in low bit rate. Moreover, with the developing fast algorithm of the SATD, we can reduce about 54% computation of the original SATD algorithm for intra 4x4 mode decision. And we can further reduce about 30% the computation of the original SAITD algorithm when computing the enhanced cost function.
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Hsieh, Wen-Han, and 謝文漢. "A New Recursive Structure for the Discrete Cosine Transform." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/79359310501168742655.
Full textAbstract:
碩士大同工學院
電機工程學系
84
In this thesis, a new recursive algorithm for the computation of the discrete cosine transform (DCT) and inverse discrete cosine transform (IDCT) is proposed. The algorithm is derived by the method that regards the DCT/IDCT as a filter type directly, so it does not need complex or dedicated mathematics like existing algorithms. Therefore, the derived processes of the proposed algorithm are easy to understand and to derive for other transforms. At the same time, the corresponding recursive filters, permitting an arbitrary-length input in natural order, are simpler and more regular than some other existing algorithms. Besides, the distribution of upper-bound values in the recursive structure for each DCT value is derived in this thesis. This distribution is used to add extra bits in the accumulator to process overflow. Finally, the roundoff error analysis for the proposed structure is presented in this thesis and some results by software simulation provide the analysis to be usful.
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Cheng, Je-Yuan, and 鄭傑元. "PAPR Reduction For OFDM By Using Discrete Cosine Transform." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/30572659501326670891.
Full textAbstract:
碩士大同大學
通訊工程研究所
92
OFDM (Orthogonal Frequency Division Multiplexing) is using multi-carries to transmit data. The transmitted data are separated into many sub-carriers as parallel transmission, instead of one carrier. Only a small amount of the data is transported on each sub-carrier, and by this lowering of the bit rate per sub-carrier. OFDM can be seen as a parallel data transmission and frequency multiplexing techniques (FDM). The approach can increase robustness against frequency selective fading and multipath immunity. OFDM is used for Terrestrial Digital TV broadcasting in Europe, Japan and Taiwan. In addition, OFDM is used in high-speed telephone line communications such as ADSL, and wireless LAN such as IEEE802.11a/g. Although OFDM has many advantages, it has a problem which is high Peak-to-average power ratio (PAPR). OFDM has high peak more than the average signal level because OFDM is composed of thousands of orthogonal waves. It is a serious defect. The defect results in these serious problems such as nonlinear distortion and increases bit error rate (BER) of receiver, next-channel Interference, etc. We must use a high-level transmitter, an high-resolution A/D and D/A converter, etc. to overcome these defects. It will increase equipment and business capital. The main purpose of this thesis is to discuss how to use discrete cosine transform (DCT) to reduce PAPR and improve application capital of OFDM.