Image processing for Tennis

The research is based on Tennis and to help umpires to get correct decisions or automate umpires' decisions using image processing.

The most important task of this research is to track the tennis ball.

Two sample videos were taken (Not an actual tennis ground).

1. Top video (To identify ball is inside or outside.)
2. Surface video (To identify the ball when the ball touches the ground.)

Each and every single frame is processed as below.

`frameLength` is the number of frames.

while(k < frameLength)  
   k=k+1;  
   aFrame = read(sufCam, k);  
   I1 =rgb2gray(aFrame);  
   J=im2double(I1);  
   H1=medfilt2(J,[3,3]);  
   i1=imadjust(H1);  
   ia =i1 >0.98;  
   H0 = read(topCam, k);  
   axes(handles.axes1);  
   imshow(H0);  
   axes(handles.axes2);  
   imshow(H1);  
     [Label,total] = bwlabel(ia,4);  
     for i=1:total  
       if(sum(sum(Label==i)) < 200 )  
         Label(Label==i)=0;  
       end  
     end  
     Sdata1 = regionprops(Label,'all');  
     Un=unique(Label);  
     my_max=0.0;  
     for i=2:numel(Un)  
     Roundness=(4*pi*Sdata1(Un(i)).Area)/Sdata1(Un(i)).Perimeter.^2;  
     my_max=max(my_max,Roundness);  
       if(Roundness==my_max)  
         ele=Un(i);  
       end  
     end  
     cen=Sdata1(ele).Centroid;  
     if(k>1 && posy > cen(1,2))  
       disp(k);  
       disp(cen(1,2));  
       k=nFrames;  
       %imshow(H1);  
       axes(handles.axes2);  
       imshow(H1);  
       hold on;  
       plot(cen(1,1),cen(1,2),'rx');
               g=rgb2gray(H0);  
               j=im2double(g);  
               k=medfilt2(j,[3,3]);  
               i2=imadjust(k);  
               ib =i2 >0.7;  
               [Label,total] = bwlabel(ib,4);  
               for i=1:total  
                 if(sum(sum(Label==i)) < 200 )  
                   Label(Label==i)=0;  
                 end  
               end  
               Sdata = regionprops(Label,'all');  
               Un=unique(Label);  
               my_max=0.0;  
               for i=2:numel(Un)  
               Roundness=(4*pi*Sdata(Un(i)).Area)/Sdata(Un(i)).Perimeter.^2;  
               my_max=max(my_max,Roundness);  
                 if(Roundness==my_max)  
                   ele=Un(i);  
                 end  
               end  
               cen2=Sdata(ele).Centroid;
               axes(handles.axes1);  
               imshow(H0);  
               hold on  
               plot(cen2(1,1),cen2(1,2),'rx');  
               disp(cen2(1,1));  
               disp(cen2(1,2));  
               textLabel = sprintf('X value = %f', cen2(1,1));  
               set(handles.text5, 'String', textLabel);  
               textLabel = sprintf('Y value = %f', cen2(1,2));  
               set(handles.text6, 'String', textLabel); 
               global border holdt;  
               border = str2double(get(handles.edit1,'string'));  
                % check whether ball inside or not                
               if(cen2(1,2) < border && holdt ==1)  
                 set(handles.text9, 'String', 'IN');  
               end  
               if(cen2(1,2) < border && holdt ==0)  
                 set(handles.text9, 'String', 'OUT');  
               end  
               if(cen2(1,2) > border && holdt ==0)  
                 set(handles.text9, 'String', 'IN');  
               end  
               if(cen2(1,2) > border && holdt ==1)  
                 set(handles.text9, 'String', 'OUT');  
               end
     end 
     posy = cen(1,2);  
     textLabel = sprintf('Y value = %f', cen(1,2));  
     set(handles.text4, 'String', textLabel);  
     disp(cen(1,2));  
     %disp(cen(1,2));  
 end

Demonstration with MATLAB GUIs

The red cross indicates that the ball was detected.