how to obtain gray values

Hi
I need to obtain the 2 representative gray values of an image. So i need MOMENT PRESERVING THRESHOLDING code.can any one give me example.

http://www.cs.tut.fi/~ant/histthresh/ThreshComp.pdf

i found the moment preserving code in java , but i need it in matlab

http://mirror.transact.net.au/pub/sourceforge/s/project/sv/svenlib/src/sven/segmentation/Thresholders.java