# Image and Signal Processing Using Matlab

Updated on September 14, 2017

## 1. Image Processing Using Wiener Filter

The Wiener filter can be used to filter out the noise from the corrupted signal to provide an estimate of the underlying signal of interest. The Wiener filter is based on a statistical approach, and a more statistical account of the theory is given in the minimum mean square error estimator article.

## 2. Audio Sigmal Processing Using Fdatool

The audio must be in wav format and if you don`t have it, and then you can make it through many programs available on the Internet.

By fdatool, we can design high-pass or lowpass or bandpass filters. Also, digital filters may be IIR or FIR; In my case I`m designing a highpass filter and I`m trying to eliminate the deep voice.

In this example we will make a high pass filter. The steps are the following:
put the command > fdatool

When the window opens, we write the following information:

Highpass filter
Type IIR - Elliptic
Fs = 8000 Hz
Fstop = 1500 Hz
Fpass = 2000 Hz
Astop = 60 dB
Apass = 1 dB

Click on Design Filter

Fdatool Window

Right-click on:
Structure> Current filter information> convert to single section

Then select:
File> Export ...

We give a name to the numerator and denominator of the filter.

Finally click on Export and save the project.

Code:

In the Matlab code we have to put the audio path that we will process and the name of the audio that we will create. When we run the code we will have audio signal processed in the same folder as the original audio signal.

## Code:

yt=filter(NumHp,DenHp,xt);

soundsc(xt);

pause(2);

soundsc(yt);

fvtool(xt);

fvtool(yt);

%save the audio

wavwrite(yt,'Audio01.wav'

## 3. Plotting Fourier Transform Functions

In this experience we can play with the functions of the Fourier Transform: rectangular, triangle, exponential, decaying oscilllation and Gauss.

## 4. Bandpass RLC Circuit

We can create a simulator of an RLC circuit by using Matlab. Here we can change the type of filter and the values of the resistance, capacitance and inductance and consequently the diagrams are varied.

## 5. Plotting Riemann Z Function

To graph the Riemann Z function we can use the mupad tool and insert the following commands shown in the image.

## Commands:

plotfunc2d(abs(zeta(1/2 + y*I)), y = 0..30, Mesh = 500)

plotfunc2d(abs(zeta(1/2 + y*I)), y = 0..30, Mesh = 500, AxesTitles = ["y", "zeta"])

plotfunc2d(abs(zeta(1/2 + y*I)), y = 0..50, Mesh = 500, AxesTitles = ["y", "zeta"])

fplot (abs(zeta(1/2+y*I)),[0..30])

zeta(-2)

zeta(0)

zeta(2)

zeta(1 + I, 1)

zeta(0,1)

zeta(infinity,1)

zeta(0.5 + 14.13472514*I, 2)

numeric::solve(zeta(1/2 + I*y), y = 10..20)

numeric::solve(zeta(1/2 + I*y), y = 10..22)

numeric::solve(zeta(1/2 + I*y), y = 20..26)

4

8

0

2

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