You forgot to attach your image, so we don't know what you're visualizing. What does "connected" mean to you? Do you mean like the Magic Wand in Photoshop? Do you mean like in the same blob in a binary image? I have no (definitive) idea. In the meantime, until we see your image and explanation, see the attached Magic Wand demo, if you have a gray scale image, and look into regionprops(), if you have a binary image.
props = regionprops(binaryImage, 'PixelList');
props has a list of all (x,y) locations of all pixels in all blobs.
