were to introduce hold on command

I  have a image in which i have to draw a circle over it,i have to draw circles in many places in the image ,please tell how to procees,i saw a code in matlab central it draws only one circle ,but how to draw many circles on a image manually ,i have to click on image and have to draw circle

http://www.mathworks.com/matlabcentral/fileexchange/23121-circle-on-image

i edited from above link but the thing is that i have to draw many circle on one image ,please tell where i have to write hold on command  

code

where k is my image 

function [] = circle_saptha(k)

ok = 0;
while ok~=1
    % figure;

      imshow(k);

      pt = ginput(2)

      x1 = pt(1,1);
      y1 = pt(1,2);
      x2 = pt(2,1);
      y2 = pt(2,2);
      xpt = [x1 x2];
      ypt = [y1 y2];
      %line(x,y); % Enablw this for draw rectangle on circle

      r = sqrt((x2-x1)^2 + (y2-y1)^2)

      pp=rsmak('circle',r,[x1 y1]);
      % figure;
      % imshow(k)
      fnplt(pp);
      line(xpt,ypt);

      xtl = x1-r;
      xtr = x1+r;
      xbl = x1-r;
      xbr = x1+r;

      ytl = y1+r;
      ytr = y1+r;
      ybl = y1-r;
      ybr = y1-r;

      x = [xtl xtr xbr xbl xtl];
      y = [ytl ytr ybr ybl ytl];
      %line(x,y);

      for i=1:size(k,1)
          for j=1:size(k,2)
              x2 = j;
              y2 = i;
              val = floor(sqrt((x2-x1)^2 + (y2-y1)^2));
              if(val == floor(r))
                  nim(i,j,1) = 255;
                  nim(i,j,2) = 0;
                  nim(i,j,3) = 0;
              else
                  nim(i,j,1) = k(i,j,1);
                  nim(i,j,2) = k(i,j,2);
                  nim(i,j,3) = k(i,j,3);
              end
          end
      end
      imshow(nim);

      ok = (menu('Do u want to draw another circle?','No','Yes')==1)
      imshow(nim);
  end
  end

Answer 1

[Teja Muppirala]

You keep overwriting "nim" with the same original "k". You can fix it easily:

Step 1. Change these lines:

ok = 0;
while ok~=1
    % figure;
      imshow(k);

to this:

ok = 0;
nim = k;
while ok~=1
    % figure;
      imshow(nim);

Step 2. Delete these three lines:

   nim(i,j,1) = k(i,j,1);
   nim(i,j,2) = k(i,j,2);
   nim(i,j,3) = k(i,j,3);

[FIR]

same error

[Teja Muppirala]

Are you sure? Run this:

k = imread('peppers.png');
ok = 0;
nim = k;
while ok~=1
    % figure;
    imshow(nim);
    pt = ginput(2)
    x1 = pt(1,1);
    y1 = pt(1,2);
    x2 = pt(2,1);
    y2 = pt(2,2);
    xpt = [x1 x2];
    ypt = [y1 y2];
    %line(x,y); % Enablw this for draw rectangle on circle
    r = sqrt((x2-x1)^2 + (y2-y1)^2)
    %line(x,y);
    for i=1:size(k,1)
        for j=1:size(k,2)
            x2 = j;
            y2 = i;
            val = floor(sqrt((x2-x1)^2 + (y2-y1)^2));
            if(val == floor(r))
                nim(i,j,1) = 255;
                nim(i,j,2) = 0;
                nim(i,j,3) = 0;
            else
              end
          end
      end
      imshow(nim);      ok = (menu('Do u want to draw another circle?','No','Yes')==1)
      imshow(nim);
  end

Answer 2

[Jan]

A simplified version:

while ok~=1
  imshow(k);
  nim = <modified k>
  imshow(nim);
  ok = (menu('Do u want to draw another circle?','No','Yes') == 1);
  imshow(nim);
end

Now nim is overwritten each time based on k. Perhaps you want:

nim = k;
while ok~=1
  nim = <modified nim>
  imshow(nim);
  ok = (menu('Do u want to draw another circle?','No','Yes') == 1);
end

[FIR]

same problem exist again

nim = k;
while ok~=1
  nim =nim

%codes above

    imshow(nim);
    ok = (menu('Do u want to draw another circle?','No','Yes') == 1);
  end

[Jan]

"nim = nim"?! Does "codes above" mean that you insert this again:

if(val == floor(r))
  nim(i,j,1) = 255;
  nim(i,j,2) = 0;
  nim(i,j,3) = 0;
else
  nim(i,j,1) = k(i,j,1);
  nim(i,j,2) = k(i,j,2);
  nim(i,j,3) = k(i,j,3);
end

Then nim is still filled with the values of the original k.

Please note, that I neither have understood, what you want to achieve, nor which problem occurs. I still do not know, what "the same problem" is. So please explain this short and clear: What happens and what do you want?

[FIR]

The code above draws circle on imagaes one by one,i want to draw many circles on same image

[Jan]

Then you should not insert the values of "k" in each iteration, but keep the values of "nim".