1 files changed, 3 insertions, 0 deletions
diff --git a/src/image.h b/src/image.h
index 4ba9e5f9..0479debc 100644
--- a/src/image.h
+++ b/src/image.h
@@ -85,6 +85,9 @@ struct image {
 	/* Wavelength must always be given */
 	double			lambda;		/* Wavelength in m */
 
+	/* Incident intensity (if unknown, put 1.0) */
+	double			f0;
+
 	int			width;
 	int			height;