How to draw filled contours on the top of another filled contour with different filled color/intensity?

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Hi, I use OpenCV 3.0 and I have a shape A to detect. (See the attachment picture).

My aim is to detect the shape A and draw the contour with filled contour using the same intensity for each contour (1 dimension matrix only). The idea is to give the inner circles higher intensity over the outer as shown by C on the attachment.

I can detected the circles using thresholding and contour detection. However, when I loop on the detected contour to draw the contours, the result is one contour with the same intensity only as shown by B on the attachment picture.

it seems like the looping is not adding the intensity on each iteration.

can someone help me out ?? Thanks.