We have found good BiModal match of the Histogram.  Having two curves (Gaussian or Laplacian) what is the suitable algorithm to choose the threshold?  Presently we choose the lowest point between the peaks of two components, but now I have doubts about this.  Should it be the intersection of 2 curves instead?

BiModal Laplacian histogram segmentation (first result):

This is simplistic global optimization (without extremum checking so did not perform as well as BiGaussian with the same number of iterations = 200K)