how do I detect object from a set of images

I am trying to detect an object from an image.My code is as follows:

function tri=ball_detection()
% A= imread('greyscale.jpg');
  
 B= rgb2gray(imread('C:\Users\Tipu_Standard\Desktop\MatlabhelpImage\original12.jpg'));
          
          A=adapthisteq(B);
          % Display the original image
          figure,imshow(A);
          distance =0;
angle=0;
 rmin=8;
  rmax=40;
          % Find all the circles with radius >= 15 and radius <= 30
          
%           [centersbright,radiibright] = imfindcircles(A,[rmin rmax],'Objectpolarity','bright');
          [centersdark,radiidark] = imfindcircles(A,[rmin rmax],'Objectpolarity','dark');

          
       k=numel(radiidark);
 
          viscircles(centersdark,radiidark ,'EdgeColor','b');
          
if(k==0)
    z=0;
else
  z=1;
  p=2*radiidark;
  f=2.1;
  w=62;
  h=144;
 s=2.88;
 distance=(f*w*h)/(p*s);
a=(192/2)-centersdark(1); 
b=144-centersdark(2);
angle=atan2(a,b)*(180/pi);
end
tri=[z,distance,angle];
end