Solved by Mona_Jalal in post #8 
              
              
                [Screenshot_2020-10-16_03-23-51] 
##[8, 600, 800] --> [8,3,600,800]
t1 = torch.rand((8,600,800))
t1 = t1.unsqueeze(1)
t1 = torch.cat((t1, t1, t1), 1)
t1.shape