Setting parameters to compute HoG

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My image is of size 128x128. Should I use a win_Size of 128x128 as well? And how to select values for the other parameters as well: HOGDescriptor(Size win_size=Size(128, 128), Size block_size=Size(16, 16), Size block_stride=Size(8, 8), Size cell_size=Size(8, 8), int nbins=9, double win_sigma=DEFAULT_WIN_SIGMA, double threshold_L2hys=0.2, bool gamma_correction=true, int nlevels=DEFAULT_NLEVELS)

I have seen the explanation at http://docs.opencv.org/2.4/modules/gp... but it is not clear enough on how to set the parameters properly.