Index: trunk/ppStack/src/ppStackMatch.c
===================================================================
--- trunk/ppStack/src/ppStackMatch.c	(revision 25313)
+++ trunk/ppStack/src/ppStackMatch.c	(revision 25376)
@@ -161,4 +161,38 @@
      return unbinned;
 }
+
+// Renormalise a readout's variance map
+bool stackRenormaliseReadout(const pmConfig *config, // Configuration
+                             pmReadout *readout      // Readout to renormalise
+    )
+{
+    bool mdok; // Status of metadata lookups
+
+    psMetadata *recipe = psMetadataLookupPtr(NULL, config->recipes, PPSTACK_RECIPE); // Recipe for ppStack
+    psAssert(recipe, "Need PPSTACK recipe");
+
+    if (!psMetadataLookupBool(&mdok, recipe, "RENORM")) return true;
+
+    int num = psMetadataLookupS32(&mdok, recipe, "RENORM.NUM");
+    if (!mdok) {
+        psError(PS_ERR_BAD_PARAMETER_VALUE, true, "RENORM.NUM is not set in the recipe");
+        return false;
+    }
+    float minValid = psMetadataLookupF32(&mdok, recipe, "RENORM.MIN");
+    if (!mdok) {
+        psError(PS_ERR_BAD_PARAMETER_VALUE, true, "RENORM.MIN is not set in the recipe");
+        return false;
+    }
+    float maxValid = psMetadataLookupF32(&mdok, recipe, "RENORM.MAX");
+    if (!mdok) {
+        psError(PS_ERR_BAD_PARAMETER_VALUE, true, "RENORM.MAX is not set in the recipe");
+        return false;
+    }
+
+    psImageMaskType maskBad = pmConfigMaskGet("BLANK", config); // Bits to mask
+
+    return pmReadoutVarianceRenormalise(readout, maskBad, num, minValid, maxValid);
+}
+
 
 
@@ -502,4 +536,9 @@
     }
 
+    if (!stackRenormaliseReadout(config, readout)) {
+        psFree(rng);
+        psFree(bg);
+        return false;
+    }
 
     // Measure the variance level for the weighting