how can i calculate area enclosed by contour?

I used snake to enclosed the left ventricle; how can i calculate area enclosed by contour?

Answer 1

[Image Analyst]

If you used activecontour, it returns a binary image, so you simply label it and call regionprops:

labeledImage = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'Area');
allAreas = [measurements.Area];

[Image Analyst]

dziri's "Answer" moved here because it's a reply to me, not an answer to the original question:

I used this code, but I find the same areas for different images. Same area in left ventricle when diastole and systole.

nb = im2bw(I, graythresh(I))
labeledImage = bwlabel(nb);
measurements = regionprops(labeledImage, 'Area');
allAreas = [measurements.Area]

allAreas =
        4096

I think that this area is the total area of image not of the Region of interest.

How do I calculate area of region of interest enclosed by contour?

[Image Analyst]

It's highly doubtful that a simple-minded routine like graythresh() and im2bw() will successfully segment out the ventricle. Maybe it does, but I doubt it. Can you upload the images?

The code looks good, though I'm very suspicious that it found only one area instead of lots of them. So I need to see the images. Please upload BOTH images.

[dziri halima]

thinks sir; these some image and this the code

clc;  clear all;close all;
   % Read in the cardiac image
  b = imread('c:/image/e1.jpg');
    b=b(:,:,1);
    a=fspecial('average',[5 5]);
    G=imfilter(b,a);
    [row,col]=size(G);
    G=G(:,:,1);
    I=double(G);
    figure(1);
    imdisp(I);
    title('Original image');
   % Compute its edge map
     I0 = gaussianBlur(I,1);
     II=1-I0/255;  %
     [u1,v1] = gradient(II); %---------- Compute its edge map
     f =sqrt(u1.^2+v1.^2); 
     figure(2)
     imdisp(f);
     title('Step Edge map');
   % Compute the GVF of the edge map f
   %      disp('display AGVF force field')  
   %    [u,v] = MyADF(f, weights,iter,sigma,deltat,fil,show)
        [u,v] = MyADF(f,[0 0.05],50,0.5,0.5,'null','ns');
        mag = sqrt(u.*u+v.*v);
         px = u./(mag+1e-10); py = v./(mag+1e-10); 

           % display the GVF 
           figure(3);
      imdisp(I);
            hold on
           quiver(px,py,'r','LineWidth',1);
            title('Adaptive GVF field');
  hold off

% initialization of snake
  figure(4);
  imdisp(I);
    x =35+5*cos(0:0.1:2*pi);
    y =35+5*sin(0:0.1:2*pi);
    [x,y] = snakeinterp(x,y,1,0.2);
  hold on, plot([x;x(1,1)],[y;y(1,1)],'r--','LineWidth',1);
 hold off
  pause(1);      
%%snake parameters
ITER=5;
alpha=0.1;
beta=0.1;
gamma=1;
kappa=0.1;
%%snake deformation
 figure(5),
imdisp(I); 
hold on, plot([x;x(1,1)],[y;y(1,1)],'r--','LineWidth',1)
    for i=1:ITER
        [x,y] = snakedeform(x,y,alpha,beta,gamma,kappa,px,py,5);
        [x,y] = snakeinterp(x,y,1,0.5);
       hold on
       x = x(:); y = y(:);
       plot([x;x(1,1)],[y;y(1,1)],'r','LineWidth',1);
        hold off   
        title(['Deformation in progress,  iter = ' num2str(i*5)]);
        pause(0.5);

      end  
         hold on, plot([x;x(1,1)],[y;y(1,1)],'LineWidth',1,'Color','r');

%%save the ultimate result     
    figure(6),
    imdisp(I),
    title('Result');
    hold on, plot([x;x(1,1)],[y;y(1,1)],'LineWidth',1,'Color','b');
 nb = im2bw(I, graythresh(I));
    labeledImage = bwlabel(nb);
 measurements = regionprops(labeledImage, 'Area');
allAreas = [measurements.Area]

[Image Analyst]

I don't have your functions like snakeinterp(), MyADF(), etc. So just upload the final binary images that you get after all that stuff has happened. Or else the x and y arrays in a .mat file.

[dziri halima]

this is a final images

[dziri halima]

hello sir; i do not find a soulution to my problem.

[Image Analyst]

You're just calling some automatic threshold on the image and using that to calculate the area.

nb = im2bw(I, graythresh(I));
labeledImage = bwlabel(nb);
measurements = regionprops(labeledImage, 'Area');
allAreas = [measurements.Area]

You're not even using the results of your snakes algorithm at all! Even so, I'd be surprised if the auth-thresholded image for both images gave the very same areas. But regardless, I don't think that's what you want to do. You can use the snake boundaries and pass them into poly2mask() to create a binary image from the snake boundaries.