5,705 research outputs found
Design of digital IP block for discrete cosine transform
Tato diplomová práce se zabývá návrhem IP bloku pro diskrétnà kosinovou transformaci. V~teoretické části jsou shrnuty algoritmy pro výpočet diskrétnà kosinové transformace a diskutována jejich použitelnost v~hardwaru. Zvolený algoritmus pro hardwarovou implementaci je modelován v jazyce C. Poté je popsán na RTL úrovni, verifikován a je provedena syntéza v~technologii TSMC 65 nm. Hardwarová implementace je poté zhodnocena s ohledem na datovou propustnost, plochu, rychlost and spotřebu.This diploma thesis deals with design of IP block for discrete cosine transform. Theoretical part summarizes algorithms for computation of discrete cosine transform and their hardware usability is discussed. Chosen algorithm for hardware implementation is modeled in C language. Algorithm is described at RTL level, verified and synthesized to TSMC 65 nm technology. Hardware implementation is then evaluated with respect of throughput, area, speed and power consumption.
Feedforward data-aided phase noise estimation from a DCT basis expansion
This contribution deals with phase noise estimation from pilot symbols. The phase noise process is approximated by an expansion of discrete cosine transform (DCT) basis functions containing only a few terms. We propose a feedforward algorithm that estimates the DCT coefficients without requiring detailed knowledge about the phase noise statistics. We demonstrate that the resulting (linearized) mean-square phase estimation error consists of two contributions: a contribution from the additive noise, that equals the Cramer-Rao lower bound, and a noise independent contribution, that results front the phase noise modeling error. We investigate the effect of the symbol sequence length, the pilot symbol positions, the number of pilot symbols, and the number of estimated DCT coefficients it the estimation accuracy and on the corresponding bit error rate (PER). We propose a pilot symbol configuration allowing to estimate any number of DCT coefficients not exceeding the number of pilot Symbols, providing a considerable Performance improvement as compared to other pilot symbol configurations. For large block sizes, the DCT-based estimation algorithm substantially outperforms algorithms that estimate only the time-average or the linear trend of the carrier phase. Copyright (C) 2009 J. Bhatti and M. Moeneclaey
Graph Spectral Image Processing
Recent advent of graph signal processing (GSP) has spurred intensive studies
of signals that live naturally on irregular data kernels described by graphs
(e.g., social networks, wireless sensor networks). Though a digital image
contains pixels that reside on a regularly sampled 2D grid, if one can design
an appropriate underlying graph connecting pixels with weights that reflect the
image structure, then one can interpret the image (or image patch) as a signal
on a graph, and apply GSP tools for processing and analysis of the signal in
graph spectral domain. In this article, we overview recent graph spectral
techniques in GSP specifically for image / video processing. The topics covered
include image compression, image restoration, image filtering and image
segmentation
Low-complexity Multidimensional DCT Approximations
In this paper, we introduce low-complexity multidimensional discrete cosine
transform (DCT) approximations. Three dimensional DCT (3D DCT) approximations
are formalized in terms of high-order tensor theory. The formulation is
extended to higher dimensions with arbitrary lengths. Several multiplierless
approximate methods are proposed and the computational
complexity is discussed for the general multidimensional case. The proposed
methods complexity cost was assessed, presenting considerably lower arithmetic
operations when compared with the exact 3D DCT. The proposed approximations
were embedded into 3D DCT-based video coding scheme and a modified quantization
step was introduced. The simulation results showed that the approximate 3D DCT
coding methods offer almost identical output visual quality when compared with
exact 3D DCT scheme. The proposed 3D approximations were also employed as a
tool for visual tracking. The approximate 3D DCT-based proposed system performs
similarly to the original exact 3D DCT-based method. In general, the suggested
methods showed competitive performance at a considerably lower computational
cost.Comment: 28 pages, 5 figures, 5 table
Performance of FFT-OFDM versus DWT-OFDM under compressive sensing
In this work, we present a comparative study on the performance of Fourier-based OFDM (FFT-OFDM) and wavelet-based OFDM (DWT-OFDM) under compressive sensing (CS). Transmission over FFT-OFDM and DWT-OFDM, which has been made under different baseband modulation schemes such as Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Key (QPSK), Quadrature amplitude modulation (16QAM) and (64QAM) has been considered. From numerical simulation results, it is observed that the Wavelet-based OFDM system outperforms Fourier based OFDM when the Quadrature Amplitude Modulation is 16QAM and 64QAM within the signal to noise ratios range 30 to 40 dB. Although CS is more efficient in compression than classical compression techniques, it introduces more errors over OFDM transmission. Future directions of this work are also suggested
Photo Based 3D Walkthrough
The objective of 'Photo Based 3D Walkthrough' is to understand how image-based
rendering technology is used to create virtual environment and to develop aprototype
system which is capable ofproviding real-time 3D walkthrough experience by solely
using 2D images. Photo realism has always been an aim of computer graphics in
virtual environment. Traditional graphics needs a great amount of works and time to
construct a detailed 3D model andscene. Despite the tedious works in constructing the
3D models andscenes, a lot ofefforts need to beput in to render the constructed 3D
models and scenes to enhance the level of realism. Traditional geometry-based
rendering systems fall short ofsimulating the visual realism of a complex environment
and are unable to capture and store a sampled representation ofa large environment
with complex lighting and visibility effects. Thus, creating a virtual walkthrough ofa
complex real-world environment remains one of the most challenging problems in
computer graphics. Due to the various disadvantages of the traditional graphics and
geometry-based rendering systems, image-based rendering (IBR) has been introduced
recently to overcome the above problems. In this project, a research will be carried out
to create anIBR virtual walkthrough by using only OpenGL and C++program without
the use of any game engine or QuickTime VR function. Normal photographs (not
panoramic photographs) are used as the source material in creating the virtual scene
and keyboard is used asthe main navigation tool in the virtual environment. The quality
ofthe virtual walkthrough prototype constructed isgood withjust a littlejerkiness
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