Index: trunk/stac/src/stac.h
===================================================================
--- trunk/stac/src/stac.h	(revision 2500)
+++ trunk/stac/src/stac.h	(revision 2661)
@@ -27,4 +27,5 @@
     float frac;				// Fraction of input pixel that must be masked before the pixel is
 					// considered bad
+    float grad;				// Multiplier of the gradient
 } stacConfig;
 
@@ -129,4 +130,9 @@
 // stacRejection.c
 
+// Return the relative gradient for a given pixel
+float stacGradient(psImage *image,	// Input for which to measure the gradient
+		   int x, int y		// Coordinates at which to measure the gradient
+    );
+
 // Transform the rejection masks back to the source frame
 psArray *stacRejection(psArray *inputs,	// Input images