The image[0] should be a single item, not a batch of items.  If the shape of that is [128,3,32,32] then that would be the shape of your data.  If you print out image.shape you will get the shape of the data in the batch.  If you would like to change the shape of your data you should probably look at the construction of the __getitem__ in your dataset and see what the shape of the data that is being put in there.