title: How to see multiple images through tf.image_summary
body: <p>Problem - only one image is shown at TensorBoard</p>
  
  <p>Inspired by this 
  <a href="https://stackoverflow.com/questions/33783672/how-can-i-visualize-the-weightsvariables-in-cnn-in-tensorflow/33794463#33794463">How can I visualize the weights(variables) in cnn in Tensorflow?</a></p>
  
  <p>Here is code:</p>
  
  <pre class="lang-py prettyprint-override"><code># --- image reader ---
  # - rsq: random shuffle queue with [fn l] pairs 
  def img_reader_jpg(rsq):
      fn, label  = rsq.dequeue()
      img_b = tf.read_file(fn)
      img_u = tf.image.decode_jpeg(img_b, channels=3) 
      img_f = tf.cast(img_u, tf.float32)  
      img_4 = tf.expand_dims(img_f,0)
      return img_4, label
  
  
  # filenames and labels are pre-loaded
  fv = tf.constant(fnames)
  lv = tf.constant(ohl)
  
  rsq    = tf.RandomShuffleQueue(len(fnames), 0, [tf.string, tf.float32])
  do_enq = rsq.enqueue_many([fv, lv])
  
  # reading_op 
  image, label   = img_reader_jpg(rsq)
  
  # test: some op
  im_t     = tf.placeholder(tf.float32, shape=[None,30,30,3], name='img_tensor')
  lab_t    = tf.placeholder(tf.float32, shape=[None,2],       name='lab_tensor')
  some_op  = tf.add(im_t,im_t) 
  ims_op   = tf.image_summary("img", im_t)
  
  # service ops
  init_op    = tf.initialize_all_variables()
  
  #  run it
  with tf.Session() as sess:
  
      summary_writer = tf.train.SummaryWriter(summ_dir, graph_def=sess.graph_def)
      print 'log at:', summ_dir
  
      sess.run(init_op)
      sess.run(do_enq)
      print "rsq.size:", rsq.size().eval()
  
      for i in xrange(5):
          print "\ni:",i
  
          img_i, lab_i = sess.run([image, label]) # read image - right?
          print "I:", img_i.shape , " L:", lab_i
  
          feed_dict = {
              im_t: img_i
          }
  
          img2 = sess.run([some_op], feed_dict = feed_dict)
  
          # now summary part
          imss = sess.run(ims_op, feed_dict = feed_dict)
          #print "imss",imss
          summary_writer.add_summary(imss,i) 
  
      print "rsq.size:", rsq.size().eval()
      summary_writer.close()
  
  print 'ok'
  </code></pre>
  
  <p>Here is output: </p>
  
  <pre class="lang-py prettyprint-override"><code>log at: /mnt/code/test_00/log/2016-01-09 17:10:37
  rsq.size: 1225
  
  i: 0
  I: (1, 30, 30, 3)  L: [ 1.  0.]
  
  i: 1
  I: (1, 30, 30, 3)  L: [ 1.  0.]
  
  i: 2
  I: (1, 30, 30, 3)  L: [ 0.  1.]
  
  i: 3
  I: (1, 30, 30, 3)  L: [ 0.  1.]
  
  i: 4
  I: (1, 30, 30, 3)  L: [ 0.  1.]
  rsq.size: 1220
  ok
  </code></pre>
  
  <p>Looks ok </p>
  
  <ul>
  <li>5 [image label] pairs were delivered</li>
  <li>in case I uncomment <strong>print "imss",imss</strong> I can see 5 different buffers each with own png image </li>
  <li>op graph looks ok in TB</li>
  </ul>
  
  <p>However only one image in TB. I suspect I have missed something important about how TF is working -.i.e. what caused what at graph execution time. </p>
  
  <p>Second question: what I need to do to see result i.e. <strong>img2 = img+img</strong> in TB?</p>