diff --git a/libvips/colour/Lab2LCh.c b/libvips/colour/Lab2LCh.c
index d9bb77e2..0d86492a 100644
--- a/libvips/colour/Lab2LCh.c
+++ b/libvips/colour/Lab2LCh.c
@@ -135,6 +135,7 @@ vips_Lab2LCh_class_init( VipsLab2LChClass *class )
 	object_class->description = _( "transform Lab to LCh" );
 
 	colour_class->process_line = vips_Lab2LCh_line;
+	colour_class->interpretation = VIPS_INTERPRETATION_LCH;
 }
 
 static void
diff --git a/libvips/colour/Lab2XYZ.c b/libvips/colour/Lab2XYZ.c
index 48df050c..d6f6e4e8 100644
--- a/libvips/colour/Lab2XYZ.c
+++ b/libvips/colour/Lab2XYZ.c
@@ -168,6 +168,7 @@ vips_Lab2XYZ_class_init( VipsLab2XYZClass *class )
 	object_class->build = vips_Lab2XYZ_build;
 
 	colour_class->process_line = vips_Lab2XYZ_line;
+	colour_class->interpretation = VIPS_INTERPRETATION_XYZ;
 
 	VIPS_ARG_BOXED( class, "temp", 110, 
 		_( "Temperature" ), 
diff --git a/libvips/colour/colour.c b/libvips/colour/colour.c
index 26ec1184..1b56ab85 100644
--- a/libvips/colour/colour.c
+++ b/libvips/colour/colour.c
@@ -87,6 +87,8 @@ static int
 vips_colour_build( VipsObject *object )
 {
 	VipsColour *colour = VIPS_COLOUR( object );
+	VipsColourClass *class = VIPS_COLOUR_GET_CLASS( colour ); 
+
 	int i;
 
 #ifdef DEBUG
@@ -114,6 +116,7 @@ vips_colour_build( VipsObject *object )
 		return( -1 );
         vips_demand_hint_array( colour->out, 
 		VIPS_DEMAND_STYLE_THINSTRIP, colour->in );
+	out->Type = class->interpretation;
 
 	if( vips_image_generate( colour->out,
 		vips_start_many, vips_colour_gen, vips_stop_many, 
@@ -139,6 +142,8 @@ vips_colour_class_init( VipsColourClass *class )
 
 	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
+	class->interpretation = VIPS_INTERPRETATION_sRGB;
+
 	VIPS_ARG_IMAGE( class, "out", 100, 
 		_( "Output" ), 
 		_( "Output image" ),
diff --git a/libvips/colour/colour.h b/libvips/colour/colour.h
index 976100d6..355bf37a 100644
--- a/libvips/colour/colour.h
+++ b/libvips/colour/colour.h
@@ -77,6 +77,10 @@ typedef struct _VipsColourClass {
 	/* The buffer processor.
 	 */
 	VipsColourProcessFn process_line;
+
+	/* What to set Type to for this subclass.
+	 */
+	VipsInterpretation interpretation;
 } VipsColourClass;
 
 GType vips_colour_get_type( void );