Digital Image Processing

Lab 1

Part of the contents of this lab are from the book:

McClellan, Schafer, and Yoder, Signal Processing First, ISBN 0-13-065562-7.

Prentice Hall, Upper Saddle River, NJ 07458.

2003 Pearson Education, Inc.

Exercise 1

Generating a sound

Fs = 8000;               % Sample everything at 8000 Hz

Fo = 660;         % Use 660 Hz as the fundamental freq of each waveform

T_total = 1.2;           % Compute a total of 1.2 seconds so the sound can be played

tt = 0:(1/Fs):T_total;       % Set up the time axis

% =====  First the cosine  =====

y1 = cos(2*pi*Fo*tt);

range = 801:880;    % Only plot a part of the signal

subplot('Position',[0.1 0.8 0.8 0.15])

plot(tt(range),y1(range))

        xlabel('TIME (sec)')

        title(['SINE WAVE at ',num2str(Fo),' Hz'])

sound(y1, Fs)

Exercise 2

Saving a sound as a WAV file

fs = 8000;

ZZ =        [ (386   + j*6101);

              (-4433 + j*14024);

              (24000 - j*4498);

                  (828   - j*6760);

              (2362  + j*0)         ];

%

Fo = 100;

ff = Fo * [ 2, 4, 5, 16, 17 ];  %-- row

dur = 4/Fo;

tt = 0 : (1/fs) : dur;

xi =  exp( -2i*pi*tt'*ff );   %--- components

xx =  xi * ZZ;

%

dur_long = 1.5;

ttt = 0 : (1/fs) : dur_long;

titleFontSize=12;

labelFontSize=12;

gcaFontSize=12;

tms = tt*1000;   %--- convert to msec

% subplot('Position',[0.12 0.6 0.8 0.3])

jkl = 1;

x1 = xi(:,jkl)*ZZ(jkl);

    hp = plot( tms, real( x1 ) );

        set(hp,'LineWidth',2)

        title('x = Re(A_2 exp(j*2*pi*2*f0*t) )','FontSize',titleFontSize)

        set(gca,'FontSize',gcaFontSize)

    ylabel('Amplitude','FontSize',labelFontSize)

disp('<CR> to play sound'),  pause

xxx = real(exp( -2i*pi*ttt'*ff(jkl) )*ZZ(jkl));

soundsc( xxx, fs );

wavwrite(xxx/max(abs(xxx)),fs,16,'k02.wav')

Exercise 3

Discrete LTI systems

Try the DLTI of the book.

Exercise 4

Poles and zeros

Try the pez_31 of the book.