MATLAB Answers

## were to introduce hold on command

Asked by FIR

### FIR (view profile)

on 10 Jan 2013
Accepted Answer by Teja Muppirala

### Teja Muppirala (view profile)

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

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## 2 Answers

Answer by Teja Muppirala

### Teja Muppirala (view profile)

on 11 Jan 2013
Accepted Answer

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

on 11 Jan 2013
same error
Teja Muppirala

### Teja Muppirala (view profile)

on 11 Jan 2013
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

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Answer by Jan

on 10 Jan 2013
Edited by Jan

### Jan (view profile)

on 10 Jan 2013

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

#### 4 Comments

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Jan

### Jan (view profile)

on 10 Jan 2013
"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

### FIR (view profile)

on 11 Jan 2013
The code above draws circle on imagaes one by one,i want to draw many circles on same image
Jan

### Jan (view profile)

on 11 Jan 2013
Then you should not insert the values of "k" in each iteration, but keep the values of "nim".

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