How can i determine the amount of a substance using image processing?

Is there a way to applied a quantitative measure to an amount of substance using image processing? I have a picture with only two colors indicating particular substance. Basically it looks like a bunch of pixels variously distributed around whole area. I failed to find a way to determine how much of whole area one substance (represented by pixels of specific color) occupies. It can be percentage value of one color vs the second one, summative surface of one color, or any other measure.

Answer 1

[Image Analyst]

See my Image Segmentation Tutorial and color segmentation demos in my File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

Obviously if you want image processing advice it makes sense to show people an image rather than make them guess "blindly". If you want more advice, read this, and then attach your image to your posting with the green and brown frame icon.