morphological method extracts specific feature by erosion and
dilation. It creates a structural element specific by the shape
setting, and control erosion degree specified by value set. In
our system the shape setting is configured to extract octagon
shape. Meanwhile bottom-hat filter return the result of
subtracting input image after morphological closing operation
[21]. Hand palm region can be obtained simply by subtracting
the image after bottom-hat filter with the image without go
through the process. The detail image is shown in Fig.2.