how to do area ratio measurement?

[muks]

When threshold is applied you get this and from here on it is pretty simply. You can eliminate the black holes by applying erosion.

[lenienter]

This is easy to be done by Vision. The problem is still unsolved. I want to know the ratio of the area for each particle. If I am required to measure the black parts one by one, and then red part one by one, then I need to specify or label each particle. Then I can safely say that the two parts are from the one particle. Actually, the problem becomes more complicated when the number of particles is more than 500.