How to count small white spots on green and black background

I am working on a project where I need to count and analyze area of small white spots on a green and black background. The green image is set to a scale of 10mm which provides me with 70pixels/mm. The white spots I am trying to identify are extremely small. I am converting the image into 8 bit and then using the thresholding tool to identify spots, but I am having a problem not eliminating at least a portion of the white spots. This method also has a high error rate due to person to person variability.

Is there a way I can and measure the white spots with little variability?

Thank you for your help!

Can you share an example image?

http://tse1.mm.bing.net/th?&id=OIP.M99f5f311c3bb08a13ebd18a27c485637o0&w=238&h=179&c=0&pid=1.9&rs=0&p=0&r=0

Similar to this but it would be a green tablet with white spots on it. I would need to measure the area and occurrence of spots.