diff --git a/externs/shaka/player.js b/externs/shaka/player.js
index 300d9469c9..6345523850 100644
--- a/externs/shaka/player.js
+++ b/externs/shaka/player.js
@@ -1207,6 +1207,8 @@ shaka.extern.LanguageRole;
 
 /**
  * @typedef {{
+ *   imageHeight: number,
+ *   imageWidth: number,
  *   height: number,
  *   positionX: number,
  *   positionY: number,
@@ -1216,6 +1218,12 @@ shaka.extern.LanguageRole;
  *   width: number
  * }}
  *
+ * @property {number} imageHeight
+ *    The image height in px. The image height could be different to height if
+ *    the layout is different to 1x1.
+ * @property {number} imageWidth
+ *    The image width in px. The image width could be different to width if
+ *    the layout is different to 1x1.
  * @property {number} height
  *    The thumbnail height in px.
  * @property {number} positionX
diff --git a/lib/player.js b/lib/player.js
index 634b381cda..cbcaed70a0 100644
--- a/lib/player.js
+++ b/lib/player.js
@@ -3637,6 +3637,8 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
         positionY = Math.floor(thumbnailPosition / columns) * height;
       }
       return {
+        imageHeight: fullImageHeight,
+        imageWidth: fullImageWidth,
         height: height,
         positionX: positionX,
         positionY: positionY,
diff --git a/lib/util/stream_utils.js b/lib/util/stream_utils.js
index 3ed813b9a6..f5a753f923 100644
--- a/lib/util/stream_utils.js
+++ b/lib/util/stream_utils.js
@@ -1014,7 +1014,13 @@ shaka.util.StreamUtils = class {
 
     // The stream width and height represent the size of the entire thumbnail
     // sheet, so divide by the layout.
-    const reference = stream.segmentIndex.get(0);
+    let reference = null;
+    // Note: segmentIndex is built by default for HLS, but not for DASH, but
+    // in DASH this information comes at the stream level and not at the
+    // segment level.
+    if (stream.segmentIndex) {
+      reference = stream.segmentIndex.get(0);
+    }
     let layout = stream.tilesLayout;
     if (reference) {
       layout = reference.getTilesLayout() || layout;
@@ -1055,7 +1061,7 @@ shaka.util.StreamUtils = class {
       channelsCount: null,
       audioSamplingRate: null,
       spatialAudio: false,
-      tilesLayout: stream.tilesLayout || null,
+      tilesLayout: layout || null,
       audioBandwidth: null,
       videoBandwidth: null,
       originalVideoId: null,
diff --git a/test/player_unit.js b/test/player_unit.js
index b4775be97d..69b5e62220 100644
--- a/test/player_unit.js
+++ b/test/player_unit.js
@@ -3544,24 +3544,32 @@ describe('Player', () => {
         const thumbnail2 = await player.getThumbnails(5, 21);
         const thumbnail5 = await player.getThumbnails(5, 51);
         expect(thumbnail0).toEqual(jasmine.objectContaining({
+          imageHeight: 150,
+          imageWidth: 200,
           positionX: 0,
           positionY: 0,
           width: 100,
           height: 50,
         }));
         expect(thumbnail1).toEqual(jasmine.objectContaining({
+          imageHeight: 150,
+          imageWidth: 200,
           positionX: 100,
           positionY: 0,
           width: 100,
           height: 50,
         }));
         expect(thumbnail2).toEqual(jasmine.objectContaining({
+          imageHeight: 150,
+          imageWidth: 200,
           positionX: 0,
           positionY: 50,
           width: 100,
           height: 50,
         }));
         expect(thumbnail5).toEqual(jasmine.objectContaining({
+          imageHeight: 150,
+          imageWidth: 200,
           positionX: 100,
           positionY: 100,
           width: 100,