diff --git a/ChangeLog b/ChangeLog
index ba8b4e76..c7e0be7d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,7 +4,8 @@
 - configure spots support for "restrict"
 - reset dcm:display-range on magick read to help DICOM
 - saner im_buildlut() behaviour
-- added im_gauss_imask_sep() 
+- added im_gauss_imask_sep()
+- allow open of truncated images, but block pixel access
 
 3/3/09 started 7.17.2
 - im_magick2vips.c: allow funky bit depths, like 14 (thanks Mikkel)
diff --git a/TODO b/TODO
index 2fb18497..682d8e7a 100644
--- a/TODO
+++ b/TODO
@@ -49,6 +49,11 @@
 WONTFIX for 7.18
 ================
 
+- bilateral filtering, see:
+
+	http://en.wikipedia.org/wiki/Bilateral_filter
+	http://www.shellandslate.com/fastmedian.html
+
 - try making vips_add(), an operator as a class
 
 - need to write interpolate docs ... manpages and tutorial
diff --git a/include/vips/vips.h b/include/vips/vips.h
index 08601396..7ebbd624 100644
--- a/include/vips/vips.h
+++ b/include/vips/vips.h
@@ -359,6 +359,11 @@ typedef struct im__IMAGE {
 	GSList *evalstartfns; 	/* list of start eval callbacks */
 	GSList *preclosefns; 	/* list of pre-close callbacks */
 	GSList *invalidatefns; 	/* list of invalidate callbacks */
+
+	/* Set this to indicate a truncated file. We've been able to read the
+	 * header, but don't try mapping any of it or you'll crash.
+	 */
+	int nodata;
 } IMAGE;
 
 /* Only define if IM_ENABLE_DEPRECATED is set.
diff --git a/libsrc/iofuncs/im_init.c b/libsrc/iofuncs/im_init.c
index d41fddab..75e92951 100644
--- a/libsrc/iofuncs/im_init.c
+++ b/libsrc/iofuncs/im_init.c
@@ -31,6 +31,8 @@
  * 	- added preclose and evalstart
  * 9/8/08
  * 	- lock global image list (thanks lee)
+ * 19/3/09
+ *	- add nodata 
  */
 
 /*
@@ -168,6 +170,8 @@ im_init( const char *filename )
 	im->preclosefns = NULL;
 	im->invalidatefns = NULL;
 
+	im->nodata = 0;
+
 	if( !(im->filename = im_strdup( NULL, filename )) ) {
 		im_close( im );
 		return( NULL );
diff --git a/libsrc/iofuncs/im_open_vips.c b/libsrc/iofuncs/im_open_vips.c
index a33123d2..8ff551a5 100644
--- a/libsrc/iofuncs/im_open_vips.c
+++ b/libsrc/iofuncs/im_open_vips.c
@@ -3,6 +3,8 @@
  * 22/5/08
  * 	- from im_open.c, im_openin.c, im_desc_hd.c, im_readhist.c,
  * 	  im_openout.c
+ * 19/3/09
+ *	- block mmaps of nodata images
  */
 
 /*
@@ -914,9 +916,9 @@ im__read_header( IMAGE *image )
 	if( (length = im_file_length( image->fd )) == -1 ) 
 		return( -1 );
 	if( psize > length ) {
-		im_error( "im_openin", _( "unable to open \"%s\", %s" ),
+		im_warn( "im_openin", _( "unable to read data for \"%s\", %s" ),
 			image->filename, _( "file has been truncated" ) );
-		return( -1 );
+		image->nodata = 1;
 	}
 
 	/* Set demand style. Allow the most permissive sort.
@@ -960,7 +962,7 @@ im_openin( IMAGE *image )
 
 	size = (gint64) IM_IMAGE_SIZEOF_LINE( image ) * image->Ysize + 
 		image->sizeof_header;
-	if( size < im__mmap_limit ) {
+	if( size < im__mmap_limit && !image->nodata ) {
 		if( im_mapfile( image ) )
 			return( -1 );
 		image->data = image->baseaddr + image->sizeof_header;
@@ -981,7 +983,7 @@ im_openin( IMAGE *image )
 	return( 0 );
 }
 
-/* Open, then mmap() read/write. This is old and deprecated API, uuse
+/* Open, then mmap() read/write. This is old and deprecated API, use
  * im_vips_open() in preference.
  */
 int
diff --git a/libsrc/iofuncs/window.c b/libsrc/iofuncs/window.c
index 6539ea44..f7eac7b0 100644
--- a/libsrc/iofuncs/window.c
+++ b/libsrc/iofuncs/window.c
@@ -2,6 +2,8 @@
  * 
  * 30/10/06
  *	- from region.c
+ * 19/3/09
+ *	- block mmaps of nodata images
  */
 
 /*
@@ -217,6 +219,15 @@ im_window_set( im_window_t *window, int top, int height )
 	gint64 start, end, pagestart;
 	size_t length, pagelength;
 
+	/* Make sure this image has data.
+	 */
+	if( window->im->nodata ) {
+		im_error( "im_window_set", 
+			_( "unable to read data for \"%s\", %s" ),
+			window->im->filename, _( "file has been truncated" ) );
+		return( -1 );
+	}
+
 	/* Calculate start and length for our window.
 	 */
 	start = window->im->sizeof_header +