% Program Name:  EXMPL_01.M

% Author: W.J. Dallas.  Date: 10 Feb 95.

% Last modified: -----

% Based on:  -----



% This program generates a uniformly filled matrix, performs the

% checkerboard-equivalent quadrant shift, does a fast Fourier transform,

% takes the absolute value of the results, scales the results to the range

% 0 to 63 and displays those results as an image.  Notice the semicolon at

% the end of each line.  The semicolons are very important. They suppress

% writing all matrix values to the screen.  Should you omit a semicolon,

% you may get a very large number of characters written to the screen.

% Should this happen, you can interrupt the operation by hitting

% <Control_C> on the keyboard.



%---- BEGIN BLOCK---- FIGURE INITIALIZATION

%

% This figure initialization comes from the file PROTOTYP.M, it allows you

% to choose the figure size.  The choice is in terms of a screen size,

% for the Op_Sci Micro-computer Lab, the maximum screen size is

% 1024x768. The program automatically positions two figure windows at the

% bottom of the screen.



% Select the screen size.

 choice = menu('Screen Size','640x480','800x600','1024x768','1280x1024');

 screen_res = choice;



% Position parameters [x_first y _first x_width y_width]

% x is measured from the left of the screen with a minimum of 4.

% y is measured from the bottom of the screen with a minimum of 4.



% Set the sizes and position the figures.

 if screen_res == 1

  % 640x480

  figure_1 = [4 4 312 312];

  figure_2 = [323 4 312 312];

 elseif screen_res == 2

  % 800x600

  figure_1 = [4 4 393 393];

  figure_2 = [404 4 393 393];

 elseif screen_res == 3

  % 1024x768

  figure_1 = [4 4 504 504];

  figure_2 = [515 4 504 504];

 elseif screen_res == 4

  % 1280x1024

   figure_1 = [4 4 632 632];

   figure_2 = [643 4 632 632];

 else

   text_buffer = ' Illegal Screen-Size Choice -- EXITING';

   disp(text_buffer);

   return;

 end



% Open the first figure window, position and clear it.

 handle_1 = figure(1);

 set(handle_1,'position',figure_1);

 clf;

 clc;

 home;



% Open the second figure window, position and clear it.

 handle_2 = figure(2);

 set(handle_2,'position',figure_2);

 clf;

 clc;

 home;



% Load and set the colormaps for both figures.

 load graymap;

 figure(1);

 colormap(map);

 figure(2);

 colormap(map);

%

%---- END BLOCK ---- 



%---- BEGIN BLOCK---- FILL THE OBJECT

%

 object=ones(32,32);

%

%---- END BLOCK ---- 





%---- BEGIN BLOCK---- QUADRANT SHIFT

%

 u=fftshift2(object);

%

%---- END BLOCK ---- 





%---- BEGIN BLOCK---- FFT

%

 u=fft2(u);

%

%---- END BLOCK ---- 



%---- BEGIN BLOCK---- QUADRANT SHIFT

%

 u=fftshift2(u);

%

%---- END BLOCK ---- 





%---- BEGIN BLOCK---- ABSOLUTE VALUE^2

%

 u=(abs(u)).^2;

%

%---- END BLOCK ---- 



%---- BEGIN BLOCK---- NORMALIZE

%

 object=63*object/(max(max(object)));

 u=63*u/(max(max(u)));

%

%---- END BLOCK ---- 



%---- BEGIN BLOCK---- DISPLAY

%

 figure(1);

 image(object);

 text_buffer='  OBJECT';

 title(text_buffer);



 figure(2);

 image(u);



 text_buffer='DFT--Press <Enter> to Finish';

 title(text_buffer);



 pause;

%

%---- END BLOCK ---- 



%---- BEGIN BLOCK---- CLEAN UP AND EXIT.

%

 clear;

 close(1);

 close(2);

%

%---- END BLOCK ----

%

%!!!!!!!!!!!!!!!! END OF M-FILE