Index: trunk/psModules/src/camera/pmFPAMaskWeight.c
===================================================================
--- trunk/psModules/src/camera/pmFPAMaskWeight.c	(revision 17692)
+++ trunk/psModules/src/camera/pmFPAMaskWeight.c	(revision 17730)
@@ -404,2 +404,29 @@
     return true;
 }
+
+
+
+bool pmSubtractionMaskApply(pmReadout *readout, psMaskType maskVal)
+{
+    PM_ASSERT_READOUT_NON_NULL(readout, false);
+    PM_ASSERT_READOUT_IMAGE(readout, false);
+    PM_ASSERT_READOUT_MASK(readout, false);
+
+    int numCols = image->numCols, numRows = image->numRows; // Size of image
+    psMaskType **maskData = mask->data.PS_TYPE_MASK_DATA; // Dereference mask
+    psF32 **imageData = image->data.F32;// Dereference image
+    psF32 **weightData = weight->data.F32; // Dereference weight map
+
+    for (int y = 0; y < numRows; y++) {
+        for (int x = 0; x < numCols; x++) {
+            if (maskData[y][x] & maskVal) {
+                imageData[y][x] = NAN;
+                if (weight) {
+                    weightData[y][x] = NAN;
+                }
+            }
+        }
+    }
+
+    return true;
+}