Counting objects in an image... how 2?

As a thesis project, Im designing a piece counter using matlab. I have to
count how many metal pieces are in a given image. All metal pieces are the
same type, and can be touching each other.
I have tried converting the color image to Black and white, eroding to
stop the pieces from touching, closing the holes in the pieces and then
counting, but its no use.
How about trying to identify a feature of the pieces... I made an image so
you can see what im talking about:
Size is 53Kbytes.
http://us.f1.yahoofs.com/bc/28befec/bc/Cobre/Imagen+002+Edited.jpg?bfaHRqDBLvO_jMhV
 

Any Ideas on how can implement that?
Thanks in advance

if link does not work, try the following:

http://us.f1.yahoofs.com/bc/28befec/bc/Cobre/Explain.jpg?bfKaRqDBE6FyBsvY

"NightHawk" <nightstalker_099@yahoo.com> wrote in message
news:nfSdnTRn-uLziDTeRVn-gQ@giganews.com...
> if link does not work, try the following:
>
> http://us.f1.yahoofs.com/bc/28befec/bc/Cobre/Explain.jpg?bfKaRqDBE6FyBsvY

Both links don't work.

You might want to read up on pattern recognition and how it relates to image
processing.

Cheers
Bhaskar

It is hard to give any suggestion without seeing some sample images.
Maybe you can get some ideas from the following page.

Face Detection Project

http://www.stanford.edu/class/ee368/Project_03/project_03.html