2.7 Matlab functions and simulation

This section will contain collection of functions and simulation I made during work on this project.

1. M file to generate a disk of some radius and center. added June 9, 2008. This function returns a 2D matrix of a disk (white=1,black=0) nma_makeDisk.m

   %**************************************************** 
   %       Copyright (C) 2008 Nasser Abbasi 
   %  Free to use and modify for academic and research only 
   %*************************************************** 
   function I=nma_makeDisk(N,r,cx,cy,blackGrayLevel,whiteGrayLevel) 
   %function nma_makeDisk(N,r,cx,cy) 
   % 
   %function to make disk image 
   %r      %radius in pixels of disk 
   %N      %size of overall image in pixels, say 256 
   %cx,cy  %location of x,y of disk center relative to center of image 
   %       %so, to have the disk center in the center of the image use (0,0) 
   % 
   % by Nasser Abbasi June 9,2008 
    
   if nargin ~=6 
       error('wrong number of arguments'); 
   end 
    
   r = round(r); 
    
   [errmsg,success]=verifyParamters(N,r,cx,cy); 
   if ~success 
       error(errmsg); 
   end 
    
   I=zeros(N); 
   I(:)=blackGrayLevel; 
    
   row=(-1)*cy+ceil(N/2); col=cx+ceil(N/2);  %adjust to center it in the image 
   for y=1:N 
       for x=1:N 
           d = sqrt((x-col)^2+(y-row)^2); 
           if d<=r 
               I(y,x)=whiteGrayLevel; 
           end 
       end 
   end 
    
   end 
   %%%%%%%%%%%%%%%%%%% 
   % Called from above function to validate input 
   % 
   %%%%%%%%%%%%%%%%%%% 
   function [errmsg,success]=verifyParamters(N,r,cx,cy) 
   errmsg=''; 
   success=0; 
    
   if ~isnumeric(N) || ~isnumeric(r)||~isnumeric(cx)||~isnumeric(cy) 
       errmsg='invalid argument type. Numerical values expected'; 
       return; 
   end 
    
   if ~(ceil(N) == floor(N)) 
       errmsg='N, size of image must be integer'; 
       return; 
   end 
    
   if ~(ceil(cx) == floor(cx)) 
       errmsg='cx, x-coordinates of disk must be integer'; 
       return; 
   end 
    
   if ~(ceil(cy) == floor(cy)) 
       errmsg='cy, y-coordinates of disk must be integer'; 
       return; 
   end 
    
   if abs(cx)>floor(N/2) || abs(cy)>floor(N/2) 
       errmsg='coordinates of center of disk outside image'; 
       return; 
   end 
    
   if r>floor(N/2) 
       errmsg='radius is too large, must be less than half the image size'; 
       return; 
   end 
    
   success=1; 
   end      
   

2. This file is a driver for the above function. Shows examples of how to call the function nma_driver_makeDisk.m

   %**************************************************** 
   %       Copyright (C) 2008 Nasser Abbasi 
   %  Free to use and modify for academic and research only 
   %*************************************************** 
    
   %script to test the function nma_makeDisk(N,r,cx,cy) 
   %a little simulation of a disk moving in 4 different configurations 
   %Nasser Abbasi 
    
   close all; clear all; 
    
   radius =25; 
   N=256; 
   A=nma_makeDisk(N,radius,0,0,0,255); 
    
   radius=25;   %in pixels radius of disk 
   N=256;       %size of overall image in pixels 
    
   cx1=-N/2:N/2-1; cy1=-N/2:N/2-1; %move it along the diagonal 
   cx2=20;         cy2=-N/2:N/2-1; %move it up and down, off center 
    
   angle=linspace(0,2*pi,N); %move it in a circle around center 
   rho=ones(1,N)*radius*3; 
   [cx3,cy3] = pol2cart(angle,rho); 
   cx3=round(cx3); 
   cy3=round(cy3); 
    
   %move it in a circle off center 
   cx4=10+cx3;  cy4=10+cy3; 
    
   h=figure(1); 
   set(h,'DoubleBuffer','on'); 
   colormap(gray); 
    
   figure; 
   N=256; 
   radius=10; 
   CX=20;         CY=-N/2:N/2-1; %move it up and down, off center 
   CX2=-20; 
   for i=1:N 
       A=nma_makeDisk(N,radius,CX,CY(i),0,255); 
       B=nma_makeDisk(N,radius,CX2,CY(i),0,255); 
       imshow(A+B,[]); 
       drawnow; 
   end 
    
   for i=1:N 
       subplot(2,2,1); 
       imshow(nma_makeDisk(N,radius,cx1(i),cy1(i)),[]); 
       line([1,N],[N/2,N/2],'Color','white'); 
       line([N/2,N/2],[1,N],'Color','white'); 
       line([1,N],[N,1],'Color','white','LineStyle',':'); 
       title('along the diagonal'); 
    
       subplot(2,2,2); 
       imshow(nma_makeDisk(N,radius,cx2,cy2(i)),[]); 
       line([1,N],[N/2,N/2],'Color','white'); 
       line([N/2,N/2],[1,N],'Color','white'); 
       line([cx2+N/2,cx2+N/2],[N,1],'Color','white','LineStyle',':'); 
       title('vertical off center'); 
    
       subplot(2,2,3); 
       imshow(nma_makeDisk(N,radius,cx3(i),cy3(i)),[]); 
       line([1,N],[N/2,N/2],'Color','white'); 
       line([N/2,N/2],[1,N],'Color','white'); 
       %plot(cx3,cy3,'Color','white','LineStyle',':'); 
       title('circle centered at center'); 
    
       subplot(2,2,4); 
       imshow(nma_makeDisk(N,radius,cx4(i),cy4(i)),[]); 
       line([1,N],[N/2,N/2],'Color','white'); 
       line([N/2,N/2],[1,N],'Color','white'); 
       %plot(cx4,cy4,'Color','white','LineStyle',':'); 
       title('circle centered off center'); 
    
       drawnow; 
   end