Buffer 0 appears to be the value, no matter if the histogram is green or red
Buffer 1 is the value of the green histogram, and when the histogram is red the value is 0
Buffer 2 is the value of the red histogram, and when the histogram is green the value is 0
So the buffers looks fine and it depends on what is needed. If you want to detect the moment when the histogram turns into green, then something like this: http://fxdreema.com/shared/jjiYO4yBc