Index: trunk/ppSub/src/ppSubBackground.c
===================================================================
--- trunk/ppSub/src/ppSubBackground.c	(revision 29937)
+++ trunk/ppSub/src/ppSubBackground.c	(revision 41382)
@@ -33,4 +33,6 @@
     psAssert(psphotRecipe, "Need PSPHOT recipe for binning");
 
+    bool doApplyMaskNaN = psMetadataLookupBool(&mdok, ppSubRecipe, "APPLY.PIXELNAN"); // NaN the pixels underneath masks
+
     psImageMaskType maskBad = pmConfigMaskGet("BLANK", config); // Bits to mask
 
@@ -64,9 +66,11 @@
         for (int x = 0; x < numCols; x++) {
 	    // special case 1: NAN the masked pixels
-            if (mask && mask->data.PS_TYPE_IMAGE_MASK_DATA[y][x] & maskBad) {
+            if(doApplyMaskNaN) {
+              if (mask && mask->data.PS_TYPE_IMAGE_MASK_DATA[y][x] & maskBad) {
                 image->data.F32[y][x] = NAN;
 		continue;
-            } 
-	    // special case 1: NAN & mask pixels without a valid background model
+              } 
+            }
+	    // special case 2: NAN & mask pixels without a valid background model
 	    float value = psImageUnbinPixel(x + 0.5, y + 0.5, modelImage, binning); // Background value
 	    if (!isfinite(value)) {