diff --git a/ChangeLog b/ChangeLog
index e30eddfe..76df4922 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -31,6 +31,7 @@
 - set MAP_NOCACHE on OS X, otherwise performance dives off a cliff with 
   files larger than memory
 - removed man pages, we are all gtk-doc now
+- added VIPS_FORMAT_BIGENDIAN format flag
 
 30/11/10 started 7.24.0
 - bump for new stable
diff --git a/libvips/format/format.c b/libvips/format/format.c
index bf401c7d..22b5da6a 100644
--- a/libvips/format/format.c
+++ b/libvips/format/format.c
@@ -68,11 +68,16 @@
  * VipsFormatFlags: 
  * @VIPS_FORMAT_NONE: no flags set
  * @VIPS_FORMAT_PARTIAL: the image may be read lazilly
+ * @VIPS_FORMAT_BIGENDIAN: image pixels are most-significant byte first
  *
  * Some hints about the image loader.
  *
  * @VIPS_FORMAT_PARTIAL means that the image can be read directly from the
  * file without needing to be unpacked to a temporary image first. 
+ *
+ * @VIPS_FORMAT_BIGENDIAN means that image pixels are most-significant byte
+ * first. Depending on the native byte order of the host machine, you may
+ * need to swap bytes. See im_copy_swap().
  */
 
 /**
@@ -339,6 +344,27 @@ vips_format_get_flags( VipsFormatClass *format, const char *filename )
 
 static const char *vips_suffs[] = { ".v", NULL };
 
+int
+im_isvips( const char *filename )
+{
+	unsigned char buf[4];
+
+	if( im__get_bytes( filename, buf, 4 ) ) {
+		if( buf[0] == 0x08 && buf[1] == 0xf2 &&
+			buf[2] == 0xa6 && buf[3] == 0xb6 )
+			/* SPARC-order VIPS image.
+			 */
+			return( 1 );
+		else if( buf[3] == 0x08 && buf[2] == 0xf2 &&
+			buf[1] == 0xa6 && buf[0] == 0xb6 )
+			/* INTEL-order VIPS image.
+			 */
+			return( 1 );
+	}
+
+	return( 0 );
+}
+
 static int
 file2vips( const char *filename, IMAGE *out )
 {
@@ -366,7 +392,19 @@ vips2file( IMAGE *im, const char *filename )
 static VipsFormatFlags
 vips_flags( const char *filename )
 {
-	return( VIPS_FORMAT_PARTIAL );
+	VipsFormatFlags flags;
+	unsigned char buf[4];
+
+	flags = VIPS_FORMAT_PARTIAL;
+
+	if( im__get_bytes( filename, buf, 4 ) &&
+		buf[0] == 0x08 && 
+		buf[1] == 0xf2 &&
+		buf[2] == 0xa6 && 
+		buf[3] == 0xb6 )
+		flags |= VIPS_FORMAT_BIGENDIAN;
+
+	return( flags );
 }
 
 /* Vips format adds no new members.
diff --git a/libvips/include/vips/format.h b/libvips/include/vips/format.h
index 57bc7cad..4405c6a7 100644
--- a/libvips/include/vips/format.h
+++ b/libvips/include/vips/format.h
@@ -54,7 +54,8 @@ extern "C" {
  */
 typedef enum {
 	VIPS_FORMAT_NONE = 0,		/* No flags set */
-	VIPS_FORMAT_PARTIAL = 1		/* Lazy read OK (eg. tiled tiff) */
+	VIPS_FORMAT_PARTIAL = 1,	/* Lazy read OK (eg. tiled tiff) */
+	VIPS_FORMAT_BIGENDIAN = 2	/* Most-significant byte first */
 } VipsFormatFlags;
 
 /* Don't instantiate these things, just use the class stuff.
diff --git a/libvips/iofuncs/image.c b/libvips/iofuncs/image.c
index 220984a2..d4433c92 100644
--- a/libvips/iofuncs/image.c
+++ b/libvips/iofuncs/image.c
@@ -382,7 +382,7 @@ vips_image_finalize( GObject *gobject )
 		if( image->dtype == VIPS_IMAGE_OPENOUT )
 			(void) im__writehist( image );
 		if( close( image->fd ) == -1 ) 
-			im_error( "vips_image_finalize", 
+			im_error( "VipsImage", 
 				_( "unable to close fd for %s" ), 
 				image->filename );
 		image->fd = -1;
@@ -818,6 +818,21 @@ vips_image_build( VipsObject *object )
 			return( -1 );
 
 		if( vips_format_is_vips( format ) ) {
+			/* We may need to byteswap.
+			 */
+			VipsFormatFlags flags = 
+				vips_format_get_flags( format, 
+					image->filename );
+			gboolean bigendian = flags & VIPS_FORMAT_BIGENDIAN;
+			gboolean swap = bigendian != im_amiMSBfirst();
+			
+			if( swap ) {
+				VipsImage *real;
+
+				if( !(real = im_open_local( image, "p" );
+				image->dtype = VIPS_IMAGE_PARTIAL;
+
+
 			if( vips_open_input( image ) )
 				return( -1 );
 
@@ -835,59 +850,48 @@ vips_image_build( VipsObject *object )
 						im_amiMSBfirst() &&
 					vips_format_sizeof( image->BandFmt ) !=
 						1 ) {
-					im_error( "vips_image_build",
-						_( "open for read-"
+					im_error( "VipsImage", "%s",
+						_( "open read-"
 						"write for native format "
 						"images only" ) );
 					return( -1 );
 				}
 
-				image->dtype = VIPS_IMAGE_TYPE_OPENIN;
+				image->dtype = VIPS_IMAGE_OPENINRW;
 			}
 		}
 		else {
-			if( vips_open_lazy( image, 
-				format, filename, mode[1] == 'd' ) )
+			if( vips_open_lazy( image, format, 
+				image->filename, image->mode[1] == 'd' ) )
 				return( -1 );
 		}
 
         	break;
 
 	case 'w':
-		if( (format = vips_format_for_name( filename )) ) {
-			if( vips_format_is_vips( format ) ) {
-				if( vips_open_output( image ) )
-					return( -1 );
-			}
-			else {
-				image->dtype = VIPS_IMAGE_TYPE_PARTIAL;
-				vips_attach_save( image, 
-					format->save, filename );
-			}
-		}
-		else {
-			char suffix[FILENAME_MAX];
-
-			im_filename_suffix( filename, suffix );
-			im_error( "vips_image_build", 
-				_( "unsupported filetype \"%s\"" ), 
-				suffix );
-
+		if( !(format = vips_format_for_name( image->filename )) ) 
 			return( -1 );
+
+		if( vips_format_is_vips( format ) ) 
+			image->dtype = VIPS_IMAGE_OPENOUT;
+		else {
+			image->dtype = VIPS_IMAGE_PARTIAL;
+			vips_attach_save( image, 
+				format->save, image->filename );
 		}
         	break;
 
         case 't':
-		image->dtype = VIPS_IMAGE_TYPE_SETBUF;
+		image->dtype = VIPS_IMAGE_SETBUF;
 		image->dhint = VIPS_DEMAND_ANY;
                 break;
 
         case 'p':
-		image->dtype = VIPS_IMAGE_TYPE_PARTIAL;
+		image->dtype = VIPS_IMAGE_PARTIAL;
                 break;
 
 	default:
-		im_error( "vips_image_build", _( "bad mode \"%s\"" ), mode );
+		im_error( "VipsImage", _( "bad mode \"%s\"" ), mode );
 
 		return( -1 );
         }
diff --git a/libvips/iofuncs/util.c b/libvips/iofuncs/util.c
index 5ebb6281..aff424f3 100644
--- a/libvips/iofuncs/util.c
+++ b/libvips/iofuncs/util.c
@@ -1498,27 +1498,6 @@ im_ispoweroftwo( int p )
 		return( 0 );
 }
 
-int
-im_isvips( const char *filename )
-{
-	unsigned char buf[4];
-
-	if( im__get_bytes( filename, buf, 4 ) ) {
-		if( buf[0] == 0x08 && buf[1] == 0xf2 &&
-			buf[2] == 0xa6 && buf[3] == 0xb6 )
-			/* SPARC-order VIPS image.
-			 */
-			return( 1 );
-		else if( buf[3] == 0x08 && buf[2] == 0xf2 &&
-			buf[1] == 0xa6 && buf[0] == 0xb6 )
-			/* INTEL-order VIPS image.
-			 */
-			return( 1 );
-	}
-
-	return( 0 );
-}
-
 /* Test this processor for endianness. True for SPARC order.
  */
 int
diff --git a/libvips/iofuncs/vips.c b/libvips/iofuncs/vips.c
index 6e4e9430..93a09b6d 100644
--- a/libvips/iofuncs/vips.c
+++ b/libvips/iofuncs/vips.c
@@ -1031,16 +1031,3 @@ im_open_vips( const char *filename )
 
 	return( im );
 }
-
-IMAGE *
-im_openout( const char *filename )
-{	
-	IMAGE *image;
-
-	if( !(image = im_init( filename )) ) 
-		return( NULL );
-	image->dtype = IM_OPENOUT;
-
-	return( image );
-}
-