Index: /branches/pap_branch_20090128/ppStack/src/ppStackMatch.c
===================================================================
--- /branches/pap_branch_20090128/ppStack/src/ppStackMatch.c	(revision 21317)
+++ /branches/pap_branch_20090128/ppStack/src/ppStackMatch.c	(revision 21318)
@@ -15,4 +15,5 @@
                      PM_SOURCE_MODE_CR_LIMIT) // Mask to apply to input sources
 #define FAINT_SOURCE_FRAC 1.0e-4         // Set minimum flux to this fraction of faintest source flux
+#define COVAR_FRAC 0.01                 // Truncation fraction for covariance matrix
 
 #define TESTING                         // Enable debugging output
@@ -456,5 +457,5 @@
             readout->mask   = psMemIncrRefCounter(output->mask);
             readout->variance = psMemIncrRefCounter(output->variance);
-            readout->covariance = psMemIncrRefCounter(output->covariance);
+            readout->covariance = psImageCovarianceTruncate(output->covariance, COVAR_FRAC);
         } else {
             // Fake the convolution