title: TensorBoard: How to write images to get a steps slider?
body: <p>I'm using keras in my ML project with the <code>TensorBoard</code> callback. I have an image autoencoder and I want to visualize its progress in reconstructing some images. So I sub-classed the <code>TensorBoard</code> class as such:</p>
  
  <pre><code>class Monitor(TensorBoard):
      def on_train_begin(self, logs=None):
          super().on_train_begin(logs)
      def on_epoch_begin(self, epoch, logs=None):
  
          # 1. Get the reconstructed images
          reconstructions = Autoencoder.predict(validation[0])
  
          # 2. Generate a summary
          summary = tf.summary.image('reconstructions', expand_dims(gallery(reconstructions), axis=0), family='reconstructions')
  
          # 3. Add the summary with `epoch` as the step
          self.writer.add_summary(summary.eval(), epoch)
  
          super().on_epoch_begin(epoch, logs)
  </code></pre>
  
  <p>(the <code>gallery</code> function simply makes a single image from a batch of images)</p>
  
  <p>What I'm seeing in <code>TensorBoard</code> when running the code is <a href="https://i.stack.imgur.com/QdZtu.jpg" rel="nofollow noreferrer">this screenshot</a>.
  The images are written each with a different name, and <code>TensorBoard</code> is not able to put a single slider to switch between them.</p>
  
  <p>How can I write image summaries so that <code>TensorBoard</code> gives me a slider to choose different steps?</p>