title: Creating a Slim classifier using pretrained ResNet V2 model
body: <p>I am trying to create an image classifier that utilizes the pre-trained ResNet V2 model provided in the slim documentation.</p>
  
  <p>Here is the code so far:</p>
  
  <pre><code>import tensorflow as tf
  slim = tf.contrib.slim
  from PIL import Image
  from inception_resnet_v2 import *
  import numpy as np
  
  checkpoint_file = 'inception_resnet_v2_2016_08_30.ckpt'
  sample_images = ['carrot.jpg']
  
  input_tensor = tf.placeholder(tf.float32, shape=(None,299,299,3), name='input_image')
  scaled_input_tensor = tf.scalar_mul((1.0/255), input_tensor)
  scaled_input_tensor = tf.subtract(scaled_input_tensor, 0.5)
  scaled_input_tensor = tf.multiply(scaled_input_tensor, 2.0)
  
  
  variables_to_restore = slim.get_model_variables()
  print(variables_to_restore)
  
  init_fn = slim.assign_from_checkpoint_fn(
          checkpoint_file,
          slim.get_model_variables('InceptionResnetV2'))
  
  sess = tf.Session()
  init_fn(sess)
  arg_scope = inception_resnet_v2_arg_scope()
  with slim.arg_scope(arg_scope):
    logits, end_points = inception_resnet_v2(scaled_input_tensor, is_training=False)
  
  for image in sample_images:
    im = Image.open(image).resize((299,299))
    im = np.array(im)
    im = im.reshape(-1,299,299,3)
    predict_values, logit_values = sess.run([end_points['Predictions'], logits], feed_dict={input_tensor: im})
    print (np.max(predict_values), np.max(logit_values))
    print (np.argmax(predict_values), np.argmax(logit_values))
  </code></pre>
  
  <p>The problem is I keep getting this error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "./classify.py", line 21, in &lt;module&gt;
      slim.get_model_variables('InceptionResnetV2'))
    File "/home/ubuntu/tensorflow/local/lib/python2.7/site-packages/tensorflow/contrib/framework/python/ops/variables.py", line 584, in assign_from_checkpoint_fn
      saver = tf_saver.Saver(var_list, reshape=reshape_variables)
    File "/home/ubuntu/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/training/saver.py", line 1040, in __init__
      self.build()
    File "/home/ubuntu/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/training/saver.py", line 1061, in build
      raise ValueError("No variables to save")
  ValueError: No variables to save
  </code></pre>
  
  <p>So it seems TF/Slim is unable to find any variables and this is made clear when I call:</p>
  
  <pre><code>variables_to_restore = slim.get_model_variables()
      print(variables_to_restore)
  </code></pre>
  
  <p>As it outputs an empty array.</p>
  
  <p>How can I go about using the pre-trained model?</p>