diff --git a/floatimg.h b/floatimg.h
index a3e5d03a..3990ca8b 100644
--- a/floatimg.h
+++ b/floatimg.h
@@ -2,7 +2,7 @@
  *	floatimg.h
  */
 
-#define		FIMG_VERSION	73
+#define		FIMG_VERSION	74
 
 /*
  *	in memory descriptor
@@ -46,6 +46,7 @@ int   fimg_fileinfo(char *fname, int *datas);
 int   fimg_plot_rgb (FloatImg *head, int x, int y, float r, float g, float b);
 int   fimg_clear(FloatImg *fimg);
 int   fimg_add_rgb(FloatImg *head, int x, int y, float r, float g, float b);
+int   fimg_rgb_constant(FloatImg *head, float r, float g, float b);
 
 
 int fimg_images_compatible(FloatImg *a, FloatImg *b);