Fourier analysis

Dct Matlab Code

A discrete cosine transform (DCT) expresses a finite sequence of data points in terms of a sum of cosine functions oscillating at different frequencies. DCTs are important to numerous applications in science and engineering, from lossy compression of audio (e.g. MP3) and images (e.g. JPEG) (where small high-frequency components can be discarded), to spectral methods for the numerical solution of partial differential equations.

Directional discrete cosine transform in matlab

The following Matlab project contains the source code and Matlab examples used for directional discrete cosine transform. DDCT is demonstrated with different block size and different modes. The details algorithm can be referred at http://link.springer.com/article/10.1007/s12596-013-0148-7?no-access=true VPS Naidu "Hybrid DDCT-PCA based multi sensor image fusionJournal of Optics", Volume 43, Issue 1, pp 48-61, March 2014,    

Quick spectral analysis plots in matlab

The following Matlab project contains the source code and Matlab examples used for quick spectral analysis plots. Inputs:       data - the data for spectral analysis          K - averaging parameter, explained below       beta - beta value for the Kaiser window   out_form - spectral analysis option  samp_freq - data sampling frequency  Outputs:        out - calculated spectral estimate in form specified by out_form  Averaging Parameter:  The spectra are smoothed by averaging over windows 1/K times the full  length of data.

3 part demo use of simple matlab commands for bit reversal required in fast fourier transform or fft

The following Matlab project contains the source code and Matlab examples used for 3 part demo use of simple matlab commands for bit reversal required in fast fourier transform or fft. 3-Part Demo Uses of Simple Matlab Commands for Bit Reversed Indices Required in Fast Fourier Transform or FFT

Short time fourier transform (stft) in matlab

The following Matlab project contains the source code and Matlab examples used for short time fourier transform (stft). %% function [t,frequency,Power_spectrum]=fft_s(y,windowlength) %% Inputs : % y: input raw signal % windowlength: window length to take fast fourier transform, it is a % factor of smapling frequency for example one can enter a window length % half of the sampling frequency by enteríng 0.

2 d dct idct for jpeg compression in matlab

The following Matlab project contains the source code and Matlab examples used for 2 d dct idct for jpeg compression. to understand the Algorithm go to matlab help in page dct2 and idct2 to get the mathematical expression for M = N = 8, we can calculate the most of hard values and save it as LUTs to speed up the execution now compare our special 8X8 functions with the internal general functions use this code: A = int32(100*rand(8,8)); tic;for i = 1 : 1000 IDCT_8X8(DCT_8X8(A));end;toc; tic;for i = 1 : 1000 idct2(dct2(A));end;toc;

1 d covolution in matlab

The following Matlab project contains the source code and Matlab examples used for 1 d covolution. In mathematics and, in particular, functional analysis, convolution is a mathematical operation on two functions f and g, producing a third function that is typically viewed as a modified version of one of the original functions, giving the area overlap between the two functions as a function of the amount that one of the original functions is translated.

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