Index: trunk/psLib/src/imageops/psImageCovariance.c
===================================================================
--- trunk/psLib/src/imageops/psImageCovariance.c	(revision 27701)
+++ trunk/psLib/src/imageops/psImageCovariance.c	(revision 27702)
@@ -432,4 +432,5 @@
 
     psKernel *sum = psKernelAlloc(xMin, xMax, yMin, yMax); // Summed covariance
+    psImageInit(sum->image, 0.0);
     for (int i = 0; i < array->n; i++) {
         psKernel *covar = array->data[i]; // Covariance matrix