diff --git a/ChangeLog b/ChangeLog
index 0acacfca..d7cc19d3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,7 @@
 - remove vips_image_copy_fields() and vips_demand_hint() and add 
   vips_image_pipeline() to do both jobs
 - vipsthumbnail allows non-square bounding boxes, thanks seth
+- add vips_matrixprint()
 
 18/10/13	started 7.36.3
 - fix compiler warnings in ubuntu 13.10
diff --git a/libvips/convolution/conv.c b/libvips/convolution/conv.c
index 74d79a76..441cb550 100644
--- a/libvips/convolution/conv.c
+++ b/libvips/convolution/conv.c
@@ -74,6 +74,11 @@ vips_conv_build( VipsObject *object )
 	if( VIPS_OBJECT_CLASS( vips_conv_parent_class )->build( object ) )
 		return( -1 );
 
+	/*
+	printf( "vips_conv_build: convolving with:\n" );
+	vips_matrixprint( convolution->M, NULL ); 
+ 	 */
+
 	if( !(imsk = im_vips2imask( convolution->M, class->nickname )) || 
 		!im_local_imask( convolution->out, imsk ) )
 		return( -1 ); 
diff --git a/libvips/convolution/im_conv.c b/libvips/convolution/im_conv.c
index efa8136e..7c0a0db2 100644
--- a/libvips/convolution/im_conv.c
+++ b/libvips/convolution/im_conv.c
@@ -1011,9 +1011,9 @@ im_conv_raw( IMAGE *in, IMAGE *out, INTMASK *mask )
 	im_generate_fn generate;
 
 #ifdef DEBUG
+#endif /*DEBUG*/
 	printf( "im_conv_raw: starting with matrix:\n" );
 	im_print_imask( mask );
-#endif /*DEBUG*/
 
 	/* Check parameters.
 	 */
diff --git a/libvips/foreign/csv.c b/libvips/foreign/csv.c
index eed5d08c..75a85c6f 100644
--- a/libvips/foreign/csv.c
+++ b/libvips/foreign/csv.c
@@ -663,12 +663,11 @@ vips__matrix_body( char *whitemap, VipsImage *out, FILE *fp )
 }
 
 VipsImage * 
-vips__matrix_read( const char *filename )
+vips__matrix_read_file( FILE *fp )
 {
 	char whitemap[256];
 	int i;
 	char *p;
-	FILE *fp;
 	int width;
 	int height;
 	double scale;
@@ -680,13 +679,9 @@ vips__matrix_read( const char *filename )
 	for( p = WHITESPACE; *p; p++ )
 		whitemap[(int) *p] = 1;
 
-	if( !(fp = vips__file_open_read( filename, NULL, TRUE )) ) 
-		return( NULL );
 	if( vips__matrix_header( whitemap, fp,
-		&width, &height, &scale, &offset ) ) {  
-		fclose( fp );
+		&width, &height, &scale, &offset ) )   
 		return( NULL );
-	}
 
 	if( !(out = vips_image_new_matrix( width, height )) )
 		return( NULL );
@@ -695,28 +690,35 @@ vips__matrix_read( const char *filename )
 
 	if( vips__matrix_body( whitemap, out, fp ) ) {
 		g_object_unref( out );
-		fclose( fp );
 		return( NULL );
 	}
-	fclose( fp );
 
 	return( out ); 
 }
 
+VipsImage * 
+vips__matrix_read( const char *filename )
+{
+	FILE *fp;
+	VipsImage *out; 
+
+	if( !(fp = vips__file_open_read( filename, NULL, TRUE )) ) 
+		return( NULL );
+	out = vips__matrix_read_file( fp ); 
+	fclose( fp );
+
+	return( out );
+}
+
 int
-vips__matrix_write( VipsImage *in, const char *filename )
+vips__matrix_write_file( VipsImage *in, FILE *fp )
 {
 	VipsImage *mask;
-	FILE *fp;
 	int x, y; 
 
 	if( vips_check_matrix( "vips2mask", in, &mask ) )
 		return( -1 );
 
-	if( !(fp = vips__file_open_write( filename, TRUE )) ) {
-		g_object_unref( mask ); 
-		return( -1 );
-	}
 	fprintf( fp, "%d %d ", mask->Xsize, mask->Ysize ); 
 	if( vips_image_get_typeof( mask, "scale" ) && 
 		vips_image_get_typeof( mask, "offset" ) ) 
@@ -733,10 +735,23 @@ vips__matrix_write( VipsImage *in, const char *filename )
 	}
 
 	g_object_unref( mask ); 
-	fclose( fp ); 
 
 	return( 0 );
 }
 
+int
+vips__matrix_write( VipsImage *in, const char *filename )
+{
+	FILE *fp;
+	int result;
+
+	if( !(fp = vips__file_open_write( filename, TRUE )) ) 
+		return( -1 );
+	result = vips__matrix_write_file( in, fp );
+	fclose( fp ); 
+
+	return( result );
+}
+
 const char *vips__foreign_matrix_suffs[] = { ".mat", NULL };
 
diff --git a/libvips/foreign/csv.h b/libvips/foreign/csv.h
index 7f868c3c..15d1e090 100644
--- a/libvips/foreign/csv.h
+++ b/libvips/foreign/csv.h
@@ -48,8 +48,10 @@ int vips__csv_write( VipsImage *in, const char *filename,
 int vips__matrix_read_header( const char *filename,
 	int *width, int *height, double *scale, double *offset );
 int vips__matrix_ismatrix( const char *filename );
+VipsImage *vips__matrix_read_file( FILE *fp );
 VipsImage *vips__matrix_read( const char *filename );
 int vips__matrix_write( VipsImage *in, const char *filename );
+int vips__matrix_write_file( VipsImage *in, FILE *fp );
 
 extern const char *vips__foreign_matrix_suffs[];
 
diff --git a/libvips/foreign/foreign.c b/libvips/foreign/foreign.c
index e9bb5048..830b6240 100644
--- a/libvips/foreign/foreign.c
+++ b/libvips/foreign/foreign.c
@@ -1611,6 +1611,7 @@ vips_foreign_operation_init( void )
 	extern GType vips_foreign_save_csv_get_type( void ); 
 	extern GType vips_foreign_load_matrix_get_type( void ); 
 	extern GType vips_foreign_save_matrix_get_type( void ); 
+	extern GType vips_foreign_print_matrix_get_type( void ); 
 	extern GType vips_foreign_load_fits_get_type( void ); 
 	extern GType vips_foreign_save_fits_get_type( void ); 
 	extern GType vips_foreign_load_analyze_get_type( void ); 
@@ -1643,6 +1644,7 @@ vips_foreign_operation_init( void )
 	vips_foreign_save_csv_get_type(); 
 	vips_foreign_load_matrix_get_type(); 
 	vips_foreign_save_matrix_get_type(); 
+	vips_foreign_print_matrix_get_type(); 
 	vips_foreign_load_analyze_get_type(); 
 	vips_foreign_load_raw_get_type(); 
 	vips_foreign_save_raw_get_type(); 
diff --git a/libvips/foreign/matrixsave.c b/libvips/foreign/matrixsave.c
index dd36e045..d3e1934b 100644
--- a/libvips/foreign/matrixsave.c
+++ b/libvips/foreign/matrixsave.c
@@ -155,3 +155,75 @@ vips_matrixsave( VipsImage *in, const char *filename, ... )
 
 	return( result );
 }
+
+typedef struct _VipsForeignPrintMatrix {
+	VipsForeignSave parent_object;
+
+} VipsForeignPrintMatrix;
+
+typedef VipsForeignSaveClass VipsForeignPrintMatrixClass;
+
+G_DEFINE_TYPE( VipsForeignPrintMatrix, vips_foreign_print_matrix, 
+	VIPS_TYPE_FOREIGN_SAVE );
+
+static int
+vips_foreign_print_matrix_build( VipsObject *object )
+{
+	VipsForeignSave *save = (VipsForeignSave *) object;
+
+	if( VIPS_OBJECT_CLASS( vips_foreign_print_matrix_parent_class )->
+		build( object ) )
+		return( -1 );
+
+	if( vips__matrix_write_file( save->ready, stdout ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+static void
+vips_foreign_print_matrix_class_init( VipsForeignPrintMatrixClass *class )
+{
+	VipsObjectClass *object_class = (VipsObjectClass *) class;
+	VipsForeignClass *foreign_class = (VipsForeignClass *) class;
+	VipsForeignSaveClass *save_class = (VipsForeignSaveClass *) class;
+
+	object_class->nickname = "matrixprint";
+	object_class->description = _( "print matrix" );
+	object_class->build = vips_foreign_print_matrix_build;
+
+	foreign_class->suffs = vips__foreign_matrix_suffs;
+
+	save_class->saveable = VIPS_SAVEABLE_MONO;
+	save_class->format_table = bandfmt_matrix;
+}
+
+static void
+vips_foreign_print_matrix_init( VipsForeignPrintMatrix *matrix )
+{
+}
+
+/**
+ * vips_matrixprint:
+ * @in: image to print 
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * Print @in to %stdout in matrix format. See vips_matrixload() for a
+ * description of the format.
+ *
+ * See also: vips_matrixload().
+ *
+ * Returns: 0 on success, -1 on error.
+ */
+int
+vips_matrixprint( VipsImage *in, ... )
+{
+	va_list ap;
+	int result;
+
+	va_start( ap, in );
+	result = vips_call_split( "matrixprint", ap, in );
+	va_end( ap );
+
+	return( result );
+}
diff --git a/libvips/include/vips/foreign.h b/libvips/include/vips/foreign.h
index b3b1e79d..80dc7d32 100644
--- a/libvips/include/vips/foreign.h
+++ b/libvips/include/vips/foreign.h
@@ -421,6 +421,8 @@ int vips_matrixload( const char *filename, VipsImage **out, ... )
 	__attribute__((sentinel));
 int vips_matrixsave( VipsImage *in, const char *filename, ... )
 	__attribute__((sentinel));
+int vips_matrixprint( VipsImage *in, ... )
+	__attribute__((sentinel));
 
 int vips_magickload( const char *filename, VipsImage **out, ... )
 	__attribute__((sentinel));