Bug fix: inspect_balloon_model.ipynb

Fix bugs of not showing boxes in 1.b RPN Predictions.
TF 1.9 introduces "ROI/rpn_non_max_suppression/NonMaxSuppressionV3:0", so the original code can't work.

samples/balloon/inspect_balloon_model.ipynb

@@ -493,10 +493,12 @@
     "# Run RPN sub-graph\n",
     "pillar = model.keras_model.get_layer(\"ROI\").output  # node to start searching from\n",
     "\n",
-    "# TF 1.4 introduces a new version of NMS. Search for both names to support TF 1.3 and 1.4\n",
+    "# TF 1.4 and 1.9 introduces new versions of NMS. Search for all names to support TF 1.3~1.10\n",
     "nms_node = model.ancestor(pillar, \"ROI/rpn_non_max_suppression:0\")\n",
     "if nms_node is None:\n",
     "    nms_node = model.ancestor(pillar, \"ROI/rpn_non_max_suppression/NonMaxSuppressionV2:0\")\n",
+    "if nms_node is None: #TF 1.9-1.10\n",
+    "    nms_node = model.ancestor(pillar, \"ROI/rpn_non_max_suppression/NonMaxSuppressionV3:0\")\n",
     "\n",
     "rpn = model.run_graph([image], [\n",
     "    (\"rpn_class\", model.keras_model.get_layer(\"rpn_class\").output),\n",
@@ -553,9 +555,12 @@
     "# Show top anchors with refinement. Then with clipping to image boundaries\n",
     "limit = 50\n",
     "ax = get_ax(1, 2)\n",
-    "visualize.draw_boxes(image, boxes=rpn[\"pre_nms_anchors\"][0, :limit], \n",
-    "           refined_boxes=rpn[\"refined_anchors\"][0, :limit], ax=ax[0])\n",
-    "visualize.draw_boxes(image, refined_boxes=rpn[\"refined_anchors_clipped\"][0, :limit], ax=ax[1])"
+    "pre_nms_anchors = utils.denorm_boxes(rpn[\"pre_nms_anchors\"][0], image.shape[:2])\n",
+    "refined_anchors = utils.denorm_boxes(rpn[\"refined_anchors\"][0], image.shape[:2])\n",
+    "refined_anchors_clipped = utils.denorm_boxes(rpn[\"refined_anchors_clipped\"][0], image.shape[:2])\n",
+    "visualize.draw_boxes(image, boxes=pre_nms_anchors[:limit],\n",
+    "                     refined_boxes=refined_anchors[:limit], ax=ax[0])\n",
+    "visualize.draw_boxes(image, refined_boxes=refined_anchors_clipped[:limit], ax=ax[1])"
    ]
   },
   {
@@ -580,7 +585,7 @@
     "# Show refined anchors after non-max suppression\n",
     "limit = 50\n",
     "ixs = rpn[\"post_nms_anchor_ix\"][:limit]\n",
-    "visualize.draw_boxes(image, refined_boxes=rpn[\"refined_anchors_clipped\"][0, ixs], ax=get_ax())"
+    "visualize.draw_boxes(image, refined_boxes=refined_anchors_clipped[ixs], ax=get_ax())"
    ]
   },
   {