Solved by elbek in post #2 
              
              
                ahh, b1 and b2 had to be float. 
making this gives right value: 
b1 = torch.tensor([167, 238, 249, 276]).view(1, -1) * 1.0
b2 = torch.tensor([146, 230, 228, 268]).view(1, -1) * 1.0