Index: trunk/ppStack/src/ppStackSources.c
===================================================================
--- trunk/ppStack/src/ppStackSources.c	(revision 27725)
+++ trunk/ppStack/src/ppStackSources.c	(revision 28095)
@@ -77,8 +77,8 @@
     PS_ASSERT_VECTOR_SIZE(inputMask, sourceLists->n, false);
 
-#if defined(TESTING) && 0
+#if defined(TESTING) && 1
     {
         // Deliberately induce a major transparency difference
-        psArray *sources = sourceLists->data[1]; // Sources to correct
+        psArray *sources = sourceLists->data[0]; // Sources to correct
         for (int i = 0; i < sources->n; i++) {
             pmSource *source = sources->data[i]; // Source of interest
@@ -283,10 +283,10 @@
                 }
                 psArray *sources = sourceLists->data[i]; // Sources of interest
-                float magCorr = zp->data.F32[i] + trans->data.F32[i] - 2.5*log10(options->sumExposure);
+                float magCorr = zp->data.F32[i] - trans->data.F32[i] - 2.5*log10(options->sumExposure);
                 if (zpExpNum == numGoodImages) {
                     // Using measured zero points, so attempt to set target zero point
                     magCorr -= zpTarget;
                 }
-                options->norm->data.F32[i] = -magCorr;
+                options->norm->data.F32[i] = magCorr;
                 psLogMsg("ppStack", PS_LOG_INFO,
                          "Applying scale correction to image %d: %f mag (%f)\n",