diff --git a/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java b/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java
index 6da9502e1b..378ec602c4 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java
@@ -70,7 +70,6 @@ public final class TtmlDecoder extends SimpleSubtitleDecoder {
   private static final String ATTR_REGION = "region";
   private static final String ATTR_IMAGE = "backgroundImage";
 
-
   private static final Pattern CLOCK_TIME =
       Pattern.compile("^([0-9][0-9]+):([0-9][0-9]):([0-9][0-9])"
           + "(?:(\\.[0-9]+)|:([0-9][0-9])(?:\\.([0-9]+))?)?$");
@@ -130,7 +129,7 @@ public final class TtmlDecoder extends SimpleSubtitleDecoder {
               Log.i(TAG, "Ignoring unsupported tag: " + xmlParser.getName());
               unsupportedNodeDepth++;
             } else if (TtmlNode.TAG_HEAD.equals(name)) {
-              parseHeader(xmlParser, globalStyles, regionMap, cellResolution, imageMap);
+              parseHeader(xmlParser, globalStyles, cellResolution, regionMap, imageMap);
             } else {
               try {
                 TtmlNode node = parseNode(xmlParser, parent, regionMap, frameAndTickRate);
@@ -232,8 +231,8 @@ public final class TtmlDecoder extends SimpleSubtitleDecoder {
   private Map<String, TtmlStyle> parseHeader(
       XmlPullParser xmlParser,
       Map<String, TtmlStyle> globalStyles,
-      Map<String, TtmlRegion> globalRegions,
       CellResolution cellResolution,
+      Map<String, TtmlRegion> globalRegions,
       Map<String, String> imageMap)
       throws IOException, XmlPullParserException {
     do {
@@ -255,23 +254,21 @@ public final class TtmlDecoder extends SimpleSubtitleDecoder {
           globalRegions.put(ttmlRegion.id, ttmlRegion);
         }
       } else if(XmlPullParserUtil.isStartTag(xmlParser, TtmlNode.TAG_METADATA)){
-        parseMetaData(xmlParser, imageMap);
+        parseMetadata(xmlParser, imageMap);
       }
 
     } while (!XmlPullParserUtil.isEndTag(xmlParser, TtmlNode.TAG_HEAD));
     return globalStyles;
   }
 
-  public void parseMetaData(XmlPullParser xmlParser, Map<String, String> imageMap) throws IOException, XmlPullParserException {
+  private void parseMetadata(XmlPullParser xmlParser, Map<String, String> imageMap) throws IOException, XmlPullParserException {
     do {
       xmlParser.next();
       if (XmlPullParserUtil.isStartTag(xmlParser, TtmlNode.TAG_SMPTE_IMAGE)) {
-        for (int i = 0; i < xmlParser.getAttributeCount(); i++) {
-          String id = XmlPullParserUtil.getAttributeValue(xmlParser, "id");
-          if(id != null){
-            String base64 = xmlParser.nextText();
-            imageMap.put(id, base64);
-          }
+        String id = XmlPullParserUtil.getAttributeValue(xmlParser, "id");
+        if (id != null) {
+          String base64 = xmlParser.nextText();
+          imageMap.put(id, base64);
         }
       }
     } while (!XmlPullParserUtil.isEndTag(xmlParser, TtmlNode.TAG_METADATA));
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlNode.java b/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlNode.java
index a20b9df24f..eb17e34729 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlNode.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlNode.java
@@ -183,18 +183,24 @@ import java.util.TreeSet;
   public List<Cue> getCues(long timeUs, Map<String, TtmlStyle> globalStyles,
       Map<String, TtmlRegion> regionMap, Map<String, String> imageMap) {
 
-    TreeMap<String, SpannableStringBuilder> regionOutputs = new TreeMap<>();
-    List<Pair<String, String>> regionImageList = new ArrayList<>();
+    TreeMap<String, SpannableStringBuilder> regionTextOutputs = new TreeMap<>();
+    List<Pair<String, String>> regionImageOutputs = new ArrayList<>();
 
-    traverseForText(timeUs, false, regionId, regionOutputs);
-    traverseForStyle(timeUs, globalStyles, regionOutputs);
-    traverseForImage(timeUs, regionId, regionImageList);
+    traverseForText(timeUs, false, regionId, regionTextOutputs);
+    traverseForStyle(timeUs, globalStyles, regionTextOutputs);
+    traverseForImage(timeUs, regionId, regionImageOutputs);
 
     List<Cue> cues = new ArrayList<>();
 
     // Create image based cues
-    for (Pair<String, String> regionImagePair : regionImageList) {
+    for (Pair<String, String> regionImagePair : regionImageOutputs) {
       String base64 = imageMap.get(regionImagePair.second);
+
+      if (base64 == null) {
+        // Image ref points to invalid image, do nothing
+        continue;
+      }
+
       byte[] decodedString = Base64.decode(base64, Base64.DEFAULT);
       Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
       TtmlRegion region = regionMap.get(regionImagePair.first);
@@ -206,13 +212,13 @@ import java.util.TreeSet;
               region.line,
               region.lineAnchor,
               region.width,
-              Cue.DIMEN_UNSET
+              /* height= */ Cue.DIMEN_UNSET
           )
       );
     }
 
     // Create text based cues
-    for (Entry<String, SpannableStringBuilder> entry : regionOutputs.entrySet()) {
+    for (Entry<String, SpannableStringBuilder> entry : regionTextOutputs.entrySet()) {
       TtmlRegion region = regionMap.get(entry.getKey());
       cues.add(
           new Cue(
diff --git a/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitlePainter.java b/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitlePainter.java
index 83b3ff3d1e..b881792576 100644
--- a/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitlePainter.java
+++ b/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitlePainter.java
@@ -355,8 +355,12 @@ import com.google.android.exoplayer2.util.Util;
   }
 
   private void setupBitmapLayout() {
+    int parentWidth = parentRight - parentLeft;
+    int parentHeight = parentBottom - parentTop;
+
     // Default position
     if (cuePosition == Cue.DIMEN_UNSET) {
+      cuePositionAnchor = Cue.ANCHOR_TYPE_MIDDLE;
       cuePosition = 0.5f;
     }
 
@@ -366,13 +370,25 @@ import com.google.android.exoplayer2.util.Util;
       cueLine = 0.85f;
     }
 
-    // Default width
+    // Default width and height
     if (cueSize == Cue.DIMEN_UNSET) {
-      cueSize = 0.5f;
+      // Scale up by height to be 10% of the parent's height
+      cueBitmapHeight = 0.1f;
+
+      float heightInParent = parentHeight * cueBitmapHeight;
+      float widthInParent = heightInParent * ((float) cueBitmap.getWidth() / cueBitmap.getHeight());
+      cueSize = widthInParent / parentWidth;
+
+      // If by the previous scaling the width exceeds 50% of the parent's width
+      // then scale back to 50% by width and adjust its height to keep the aspect ratio
+      if (cueSize > 0.5f) {
+        cueSize = 0.5f;
+        widthInParent = parentWidth * cueSize;
+        heightInParent = widthInParent * ((float) cueBitmap.getHeight() / cueBitmap.getWidth());
+        cueBitmapHeight = heightInParent / parentHeight;
+      }
     }
 
-    int parentWidth = parentRight - parentLeft;
-    int parentHeight = parentBottom - parentTop;
     float anchorX = parentLeft + (parentWidth * cuePosition);
     float anchorY = parentTop + (parentHeight * cueLine);
     int width = Math.round(parentWidth * cueSize);