title: Visualizing the output of intermediate layers of cnn in pytorch
body: <p>I'm trying to visualize the output of the intermediate layers of the VGG19 network, from the torchvision module, specifically the layer, <code>conv4_2</code>. 
  I've extracted the output in a tensor of shape <code>[1, 512, 50, 50]</code>. 
  But how do I visualize an image with 512 channels?</p>