Rendering blobs without extra boxes and lines

[Pi HomeServer]

Hello,

I am able to detect blobs in a picture, i can render them in a new one but i always get boxes around each blob and with different colors.

Is there a way to remove that extra drawings and keep only the original information ?

Thank you

(I use OpenCV 2.4 on Mac OS X 10.9 and Xcode 5.0.2)