diff --git a/ChangeLog b/ChangeLog
index 6b3907e2..7bd10158 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,13 +15,15 @@
 - add subsample_mode, deprecate no_subsample in jpegsave [Elad-Laufer]
 - add vips_isdirf()
 - add PAGENUMBER support to tiff write [jclavoie-jive]
-- add all to smartcrop 
+- add "all" mode to smartcrop 
 - flood fill could stop half-way for some very complex shapes
 - better handling of unaligned reads in multipage tiffs [petoor]
 - mark old --delete option to vipsthumbnail as deprecated [UweOhse]
 - png save with a bad ICC profile just gives a warning
 - add "premultipled" option to vips_affine(), clarified vips_resize() 
   behaviour with alpha channels
+- improve bioformats support with read and write of tiff subifd pyramids
+- thumbnail exploits subifd pyramids
 
 24/4/20 started 8.9.3
 - better iiif tile naming [IllyaMoskvin]
diff --git a/libvips/include/vips/header.h b/libvips/include/vips/header.h
index 1716f386..d4d09037 100644
--- a/libvips/include/vips/header.h
+++ b/libvips/include/vips/header.h
@@ -178,6 +178,7 @@ double vips_image_get_scale( const VipsImage *image );
 double vips_image_get_offset( const VipsImage *image );
 int vips_image_get_page_height( VipsImage *image );
 int vips_image_get_n_pages( VipsImage *image );
+int vips_image_get_n_subifds( VipsImage *image );
 const void *vips_image_get_data( VipsImage *image );
 
 void vips_image_init_fields( VipsImage *image, 
diff --git a/libvips/iofuncs/header.c b/libvips/iofuncs/header.c
index dba1c767..230dfeb7 100644
--- a/libvips/iofuncs/header.c
+++ b/libvips/iofuncs/header.c
@@ -818,7 +818,7 @@ vips_image_get_page_height( VipsImage *image )
  * vips_image_get_n_pages: (method)
  * @image: image to get from
  *
- * Fetch and sanity-check VIPS_META_N_PAGES. Default to 1 if not present or
+ * Fetch and sanity-check #VIPS_META_N_PAGES. Default to 1 if not present or
  * crazy.
  *
  * This is the number of pages in the image file, not the number of pages that
@@ -840,6 +840,29 @@ vips_image_get_n_pages( VipsImage *image )
 	return(	1 );
 }
 
+/**
+ * vips_image_get_n_subifds: (method)
+ * @image: image to get from
+ *
+ * Fetch and sanity-check #VIPS_META_N_SUBIFDS. Default to 0 if not present or
+ * crazy.
+ *
+ * Returns: the number of subifds in the image file
+ */
+int
+vips_image_get_n_subifds( VipsImage *image )
+{
+	int n_subifds;
+
+	if( vips_image_get_typeof( image, VIPS_META_N_SUBIFDS ) &&
+		!vips_image_get_int( image, VIPS_META_N_SUBIFDS, &n_subifds ) &&
+		n_subifds > 1 &&
+		n_subifds < 1000 )
+		return( n_subifds );
+
+	return(	0 );
+}
+
 /**
  * vips_image_get_data: (method)
  * @image: image to get data for
diff --git a/libvips/resample/thumbnail.c b/libvips/resample/thumbnail.c
index 5a9c5296..8498ae5c 100644
--- a/libvips/resample/thumbnail.c
+++ b/libvips/resample/thumbnail.c
@@ -28,6 +28,8 @@
  * 	- smarter heif thumbnail selection
  * 12/10/19
  * 	- add thumbnail_source
+ * 2/6/20
+ * 	- add subifd pyr support
  */
 
 /*
@@ -117,6 +119,7 @@ typedef struct _VipsThumbnail {
 	VipsAngle angle; 		/* From vips_autorot_get_angle() */
 	int n_pages;			/* Pages in file */
 	int n_loaded_pages;		/* Pages we've loaded from file */
+	int n_subifds;			/* Number of subifds */
 
 	/* For openslide, we need to read out the size of each level too.
 	 *
@@ -131,6 +134,10 @@ typedef struct _VipsThumbnail {
 	int heif_thumbnail_width;
 	int heif_thumbnail_height;
 
+	/* For TIFF sources, open subifds rather than pages to get pyr layers.
+	 */
+	gboolean subifd_pyramid;
+
 } VipsThumbnail;
 
 typedef struct _VipsThumbnailClass {
@@ -199,6 +206,7 @@ vips_thumbnail_read_header( VipsThumbnail *thumbnail, VipsImage *image )
 	thumbnail->angle = vips_autorot_get_angle( image );
 	thumbnail->page_height = vips_image_get_page_height( image );
 	thumbnail->n_pages = vips_image_get_n_pages( image );
+	thumbnail->n_subifds = vips_image_get_n_subifds( image );
 
 	/* VIPS_META_N_PAGES is the number of pages in the document, 
 	 * not the number we've read out into this image. We calculate
@@ -235,15 +243,20 @@ vips_thumbnail_read_header( VipsThumbnail *thumbnail, VipsImage *image )
 	}
 }
 
-/* This may not be a pyr tiff, so no error if we can't find the layers. 
- * We just look for two or more pages following roughly /2 shrinks.
+/* Detect a TIFF pyramid made of pages following a roughly /2 shrink.
+ *
+ * This may not be a pyr tiff, so no error if we can't find the layers. 
  */
-static void
-vips_thumbnail_get_tiff_pyramid( VipsThumbnail *thumbnail ) 
+static gboolean
+vips_thumbnail_get_tiff_pyramid_page( VipsThumbnail *thumbnail ) 
 {
 	VipsThumbnailClass *class = VIPS_THUMBNAIL_GET_CLASS( thumbnail );
 	int i;
 
+#ifdef DEBUG
+	printf( "vips_thumbnail_get_tiff_pyramid_page:\n" );
+#endif /*DEBUG*/
+
 	for( i = 0; i < thumbnail->n_pages; i++ ) {
 		VipsImage *page;
 		int level_width;
@@ -252,7 +265,7 @@ vips_thumbnail_get_tiff_pyramid( VipsThumbnail *thumbnail )
 		int expected_level_height;
 
 		if( !(page = class->open( thumbnail, i )) )
-			return;
+			return( FALSE );
 		level_width = page->Xsize;
 		level_height = page->Ysize;
 		VIPS_UNREF( page );
@@ -264,10 +277,10 @@ vips_thumbnail_get_tiff_pyramid( VipsThumbnail *thumbnail )
 		 */
 		if( abs( level_width - expected_level_width ) > 5 ||
 			level_width < 2 )
-			return;
+			return( FALSE );
 		if( abs( level_height - expected_level_height ) > 5 ||
 			level_height < 2 )
-			return;
+			return( FALSE );
 
 		thumbnail->level_width[i] = level_width;
 		thumbnail->level_height[i] = level_height;
@@ -276,10 +289,74 @@ vips_thumbnail_get_tiff_pyramid( VipsThumbnail *thumbnail )
 	/* Now set level_count. This signals that we've found a pyramid.
 	 */
 #ifdef DEBUG
-	printf( "vips_thumbnail_get_tiff_pyramid: %d layer pyramid detected\n",
-	     thumbnail->n_pages );
+	printf( "vips_thumbnail_get_tiff_pyramid_page: "
+		"%d layer pyramid detected\n",
+		thumbnail->n_pages );
 #endif /*DEBUG*/
 	thumbnail->level_count = thumbnail->n_pages;
+
+	return( thumbnail->n_pages > 1 );
+}
+
+/* Detect a TIFF pyramid made of subifds following a roughly /2 shrink.
+ *
+ * This may not be a pyr tiff, so no error if we can't find the layers. 
+ */
+static gboolean
+vips_thumbnail_get_tiff_pyramid_subifd( VipsThumbnail *thumbnail ) 
+{
+	VipsThumbnailClass *class = VIPS_THUMBNAIL_GET_CLASS( thumbnail );
+	int i;
+
+#ifdef DEBUG
+	printf( "vips_thumbnail_get_tiff_pyramid_subifd:\n" );
+#endif /*DEBUG*/
+
+	/* Tell open() that we want to open subifds rather than pages.
+	 */
+	thumbnail->subifd_pyramid = TRUE;
+
+	for( i = 0; i < thumbnail->n_subifds; i++ ) {
+		VipsImage *page;
+		int level_width;
+		int level_height;
+		int expected_level_width;
+		int expected_level_height;
+
+		if( !(page = class->open( thumbnail, i )) )
+			return( FALSE );
+		level_width = page->Xsize;
+		level_height = page->Ysize;
+		VIPS_UNREF( page );
+
+		/* The main image is size 1, subifd 0 is half that.
+		 */
+		expected_level_width = thumbnail->input_width / (2 << i);
+		expected_level_height = thumbnail->input_height / (2 << i);
+
+		/* This won't be exact due to rounding etc.
+		 */
+		if( abs( level_width - expected_level_width ) > 5 ||
+			level_width < 2 )
+			return( FALSE );
+		if( abs( level_height - expected_level_height ) > 5 ||
+			level_height < 2 )
+			return( FALSE );
+
+		thumbnail->level_width[i] = level_width;
+		thumbnail->level_height[i] = level_height;
+	}
+
+	/* Now set level_count. This signals that we've found a pyramid.
+	 */
+#ifdef DEBUG
+	printf( "vips_thumbnail_get_tiff_pyramid_subifd: "
+		"%d layer pyramid detected\n",
+		thumbnail->n_pages );
+#endif /*DEBUG*/
+	thumbnail->level_count = thumbnail->n_pages;
+
+	return( TRUE );
 }
 
 static int
@@ -459,11 +536,13 @@ vips_thumbnail_open( VipsThumbnail *thumbnail )
 	g_info( "input size is %d x %d", 
 		thumbnail->input_width, thumbnail->input_height ); 
 
-	/* For tiff, we need a separate ->open() for each page to
-	 * get all the pyramid levels.
+	/* For tiff, scan the image and try to spot page-based and ifd-based
+	 * pyramids. 
 	 */
-	if( vips_isprefix( "VipsForeignLoadTiff", thumbnail->loader ) ) 
-		vips_thumbnail_get_tiff_pyramid( thumbnail );
+	if( vips_isprefix( "VipsForeignLoadTiff", thumbnail->loader ) ) {
+		if( !vips_thumbnail_get_tiff_pyramid_page( thumbnail ) )
+			vips_thumbnail_get_tiff_pyramid_subifd( thumbnail );
+	}
 
 	/* For heif, we need to fetch the thumbnail size, in case we can use
 	 * that as the source.
@@ -967,10 +1046,16 @@ vips_thumbnail_file_open( VipsThumbnail *thumbnail, double factor )
 			NULL ) );
 	}
 	else if( vips_isprefix( "VipsForeignLoadTiff", thumbnail->loader ) ) {
-		return( vips_image_new_from_file( file->filename, 
-			"access", VIPS_ACCESS_SEQUENTIAL,
-			"page", (int) factor,
-			NULL ) );
+		if( thumbnail->subifd_pyramid )
+			return( vips_image_new_from_file( file->filename, 
+				"access", VIPS_ACCESS_SEQUENTIAL,
+				"subifd", (int) factor,
+				NULL ) );
+		else
+			return( vips_image_new_from_file( file->filename, 
+				"access", VIPS_ACCESS_SEQUENTIAL,
+				"page", (int) factor,
+				NULL ) );
 	}
 	else if( vips_isprefix( "VipsForeignLoadHeif", thumbnail->loader ) ) {
 		return( vips_image_new_from_file( file->filename,