Index: trunk/ippconfig/recipes/ppStack.config
===================================================================
--- trunk/ippconfig/recipes/ppStack.config	(revision 34090)
+++ trunk/ippconfig/recipes/ppStack.config	(revision 34091)
@@ -83,6 +83,8 @@
 PSF.MODEL	STR	PS_MODEL_GAUSS	# Model for PSF generation
 
-PSF.AUTOSIZE	BOOL	TRUE		# Determine output PSF size from input PSFs?
-PSF.OUTPUT.FWHM	F32	5.0		# Target size for output PSF (if not auto-sized)
+PSF.AUTOSIZE		BOOL	TRUE		# Determine output PSF size from input PSFs?
+PSF.OUTPUT.FWHM         F32     5.0             # Target size for output PSF (if not auto-sized), -1 as mean FWHM inputs 
+PSF.OUTPUT.NFWHMSIG     F32     0.0             # N FWHM-sig to be added to the FWHMmean for PSF
+
 
 PSF.INPUT.MAX           F32  NAN
Index: trunk/ppStack/src/ppStackPSF.c
===================================================================
--- trunk/ppStack/src/ppStackPSF.c	(revision 34090)
+++ trunk/ppStack/src/ppStackPSF.c	(revision 34091)
@@ -4,8 +4,10 @@
 
 pmPSF *ppStackPSF(const pmConfig *config, int numCols, int numRows,
-                  const psArray *psfs, const psVector *inputMask)
+                  const psArray *psfs, ppStackOptions *options)
 {
     bool mdok = false;
     pmPSF *psf = NULL;
+
+    const psVector *inputMask = options->inputMask;
 
     // Get the recipe values
@@ -55,4 +57,20 @@
 	}
 
+	//MEH -- preliminary add option -1 for choosing mean FWHM of inputs. Nsig<0 for scaling +Nsig by mean
+	if (psfFWHM<0.0){
+	    float NpsfFWHMsig = psMetadataLookupF32(&mdok, recipe, "PSF.OUTPUT.NFWHMSIG"); // Nsig to include
+	    if (!mdok){
+	    	NpsfFWHMsig = 0.0;
+	    }
+	    float clippedMean = options->clippedMean;
+	    float clippedStdev = options->clippedStdev;
+	    psfFWHM = clippedMean + NpsfFWHMsig*clippedStdev;
+	    if (NpsfFWHMsig<0.0){
+	    	psfFWHM = clippedMean + NpsfFWHMsig * -1.0*clippedStdev/clippedMean;
+	    }
+	}
+
+
+
 	float Mxx = M_SQRT2 * psfFWHM / 2.35;
 
Index: trunk/ppStack/src/ppStackPrepare.c
===================================================================
--- trunk/ppStack/src/ppStackPrepare.c	(revision 34090)
+++ trunk/ppStack/src/ppStackPrepare.c	(revision 34091)
@@ -318,5 +318,5 @@
     // Generate target PSF
     if (options->convolve) {
-        options->psf = ppStackPSF(config, numCols, numRows, psfs, options->inputMask);
+        options->psf = ppStackPSF(config, numCols, numRows, psfs, options);
         psFree(psfs);
         if (!options->psf) {