Define the decoder network for reconstructing the image. It consists of three fully connected networks, as follows:

with tf.name_scope('Decoder'):

    #masked digit capsule
    v_j = tf.reshape(masked_v, shape=(batch_size, -1))

    #first fully connected layer 
    fc1 = tf.contrib.layers.fully_connected(v_j, num_outputs=512)

    #second fully connected layer
    fc2 = tf.contrib.layers.fully_connected(fc1, num_outputs=1024)

    #reconstructed image
    reconstructed_image = tf.contrib.layers.fully_connected(fc2, num_outputs=784, activation_fn=tf.sigmoid)