Index: /trunk/psModules/src/imcombine/pmSubtractionKernels.h
===================================================================
--- /trunk/psModules/src/imcombine/pmSubtractionKernels.h	(revision 14532)
+++ /trunk/psModules/src/imcombine/pmSubtractionKernels.h	(revision 14533)
@@ -21,5 +21,5 @@
     long num;                           ///< Number of kernel components (not including the spatial ones)
     psVector *u, *v;                    ///< Offset (for POIS) or polynomial order (for ISIS)
-    psVector *widths;                   ///< Gaussian widths (ISIS) or ring radius (RINGS)
+    psVector *widths;                   ///< Gaussian FWHMs (ISIS) or ring radius (RINGS)
     psVector *uStop, *vStop;            ///< Width of kernel element (SPAM,FRIES only)
     int subIndex;                       ///< Index of kernel to be subtracted (to maintain flux conservation)
@@ -49,5 +49,5 @@
 pmSubtractionKernels *pmSubtractionKernelsISIS(int size, ///< Half-size of the kernel
                                                int spatialOrder, ///< Order of spatial variations
-                                               const psVector *sigmas, ///< Gaussian widths
+                                               const psVector *fwhms, ///< Gaussian FWHMs
                                                const psVector *orders ///< Polynomial order of gaussians
                                                );
@@ -69,5 +69,5 @@
 pmSubtractionKernels *pmSubtractionKernelsGUNK(int size, ///< Half-size of the kernel
                                                int spatialOrder, ///< Order of spatial variations
-                                               const psVector *sigmas, ///< Gaussian widths
+                                               const psVector *fwhms, ///< Gaussian FWHMs
                                                const psVector *orders, ///< Polynomial order of gaussians
                                                int inner ///< Inner radius containing grid of delta functions
@@ -86,5 +86,5 @@
                                                    int size, ///< Half-size of the kernel
                                                    int spatialOrder, ///< Order of spatial variations
-                                                   const psVector *sigmas, ///< Gaussian widths
+                                                   const psVector *fwhms, ///< Gaussian FWHMs
                                                    const psVector *orders, ///< Polynomial order of gaussians
                                                    int inner, ///< Inner radius to preserve unbinned
Index: /trunk/psModules/src/imcombine/pmSubtractionStamps.c
===================================================================
--- /trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 14532)
+++ /trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 14533)
@@ -303,5 +303,5 @@
 
 
-bool pmSubtractionGenerateStamps(psArray *stamps, float sigma, int footprint,
+bool pmSubtractionGenerateStamps(psArray *stamps, float fwhm, int footprint,
                                  const pmSubtractionKernels *kernels)
 {
@@ -312,4 +312,5 @@
     int size = kernels->size + footprint; // Size of postage stamps
     int num = stamps->n;                // Number of stamps
+    float sigma = fwhm / (2.0 * sqrtf(2.0 * ln(2.0))); // Gaussian sigma
 
     for (int i = 0; i < num; i++) {
@@ -337,5 +338,5 @@
             for (int u = -size; u <= size; u++) {
                 input->kernel[v][u] = flux / sigma * 0.5 * M_2_SQRTPI * M_SQRT1_2 *
-                    expf(0.5 * (PS_SQR(u + xStamp) + PS_SQR(v + yStamp)) / PS_SQR(sigma));
+                    expf(-0.5 * (PS_SQR(u + xStamp) + PS_SQR(v + yStamp)) / PS_SQR(sigma));
             }
         }
Index: /trunk/psModules/src/imcombine/pmSubtractionStamps.h
===================================================================
--- /trunk/psModules/src/imcombine/pmSubtractionStamps.h	(revision 14532)
+++ /trunk/psModules/src/imcombine/pmSubtractionStamps.h	(revision 14533)
@@ -56,5 +56,5 @@
 /// Generate target for stamps based on list
 bool pmSubtractionGenerateStamps(psArray *stamps, ///< Stamps
-                                 float sigma, ///< Gaussian width for each stamp
+                                 float fwhm, ///< FWHM for each stamp
                                  int footprint, ///< Stamp footprint size
                                  const pmSubtractionKernels *kernels ///< Kernel basis functions