I hav an image with already plotted contours as i have performed segmentation of the image now I want to compute the area of each contour all this should be an automated procedure how do i go about this?Please help me

The image is in the jpeg format it is the cardiac mri image of a patient.We have segmented it so contours have been plotted I just need to compute the area of each contour please help me I tried using regionprops and polyarea but it's not giving the required result.Please help me