Determination of particle area in reference of the whole area

I have a video of particles going throw the region of interest. I'm interested in getting the area of all the particles in reference to the hole area of the region of interest.

As you can see, I have cropped the region of interest and seperated it from the rest of the image. Now I'm stuck with the next step because I don't really know which steps are getting me to a result. I thought about using the Image Processing Toolbox because it seems to be easier (although I have to read some images step by step), but I could also use the Computer Vision System Toolbox.

Are there some hints which functions I should use or maybe complete particle-detection-packages that I can use? I think my biggest problem is that the particles vary in shape and size nor are they only circular. Also the particles seem to have more than just one color - just like the background.

Answer 1

[Jonas Thomalla]

The answer to this is also the answer to another question I asked: click here