self.mask_global = torch.ByteTensor(1, 1, 256, 256)

self.mask_global.zero_()

real_A = torch.Tensor(16, 3, 256, 256)
real_A.narrow(1,0,1).masked_fill_(self.mask_global, 2*117.0/255.0 - 1.0)
real_A.narrow(1,1,1).masked_fill_(self.mask_global, 2*104.0/255.0 - 1.0)
real_A.narrow(1,2,1).masked_fill_(self.mask_global, 2*117.0/255.0 - 1.0)