title: pix2pixHD shows error after changing datasets
body: <p>I was trying out the pix2pixHD code from the link below.<br>
  <a href="https://github.com/NVIDIA/pix2pixHD" rel="nofollow noreferrer">https://github.com/NVIDIA/pix2pixHD</a></p>
  
  <p>The train.py worked with default images (in datasets/cityscapes). However, after changing images in the dataset, it shows the error below.</p>
  
  
  
  <pre><code>    model [Pix2PixHDModel] was created
      create web directory ./checkpoints/label2city/web...
      Traceback (most recent call last):
        File "/home/shimada/venv/py2.7/projects/Hiwi/pix2pixHD/train.py", line 58, in &lt;module&gt;
          Variable(data['image']), Variable(data['feat']), infer=save_fake)
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/modules/module.py", line 325, in __call__
          result = self.forward(*input, **kwargs)
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/parallel/data_parallel.py", line 66, in forward
          return self.module(*inputs[0], **kwargs[0])
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/modules/module.py", line 325, in __call__
          result = self.forward(*input, **kwargs)
        File "/home/shimada/venv/py2.7/projects/Hiwi/pix2pixHD/models/pix2pixHD_model.py", line 141, in forward
          fake_image = self.netG.forward(input_concat)
        File "/home/shimada/venv/py2.7/projects/Hiwi/pix2pixHD/models/networks.py", line 213, in forward
          return self.model(input)             
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/modules/module.py", line 325, in __call__
          result = self.forward(*input, **kwargs)
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/modules/container.py", line 67, in forward
          input = module(input)
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/modules/module.py", line 325, in __call__
          result = self.forward(*input, **kwargs)
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/modules/conv.py", line 277, in forward
          self.padding, self.dilation, self.groups)
        File "/home/shimada/venv/py2.7/local/lib/python2.7/site-packages/torch/nn/functional.py", line 90, in conv2d
          return f(input, weight, bias)
      RuntimeError: Given groups=1, weight[64, 36, 7, 7], so expected input[1, 39, 518, 1030] to have 36 channels, but got 39 channels instead
      THCudaCheck FAIL file=/pytorch/torch/lib/THC/generic/THCStorage.c line=184 error=59 : device-side assert triggered
      terminate called after throwing an instance of 'std::runtime_error'
        what():  cuda runtime error (59) : device-side assert triggered at /pytorch/torch/lib/THC/generic/THCStorage.c:184
      bash: line 1: 10965 Aborted                 (core dumped) env "PYCHARM_HOSTED"="1" "PYTHONUNBUFFERED"="1" "PYTHONIOENCODING"="UTF-8" "PYCHARM_MATPLOTLIB_PORT"="42188" "JETBRAINS_REMOTE_RUN"="1" "PYTHONPATH"="/home/shimada/.pycharm_helpers/pycharm_matplotlib_backend:/home/shimada/venv/py2.7/projects/Hiwi/pix2pixHD" /home/shimada/venv/py2.7/bin/python -u /home/shimada/venv/py2.7/projects/Hiwi/pix2pixHD/train.py
  </code></pre>
  
  
  
  <p>I changed the images with same size (width 2048, hight 1024), same extension (.png) and gave the same names. Why doesn't it work? </p>