I believe I answered that in your duplicate question. http://www.mathworks.com/matlabcentral/answers/122191#answer_129108 But you didn't officially mark it as "Accepted", and I don't see any of your own code posted, so either you didn't see my answer in your duplicate question, or you're waiting for me to do it for you. Again, my Image Segmentation Tutorial, which was a Pick of the Week shows you how to discriminate objects based on size.
Remember, it's your project, so I can't just do it all for you but I'm giving you a huge head start . You should take advantage of that help. All you have to do is to put your bottles on a uniform background and make slight customization to my code, which is well within your capabilities. I know you can do it, I have confidence in you because you're a smart engineer. Post your code here if you need help.
