Index: trunk/psModules/src/imcombine/pmSubtractionKernels.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionKernels.c	(revision 13383)
+++ trunk/psModules/src/imcombine/pmSubtractionKernels.c	(revision 13389)
@@ -168,4 +168,5 @@
     }
 
+    // Subtract a particular kernel in order to preserve photometric calibration across image
     kernels->subIndex = 0;
     assert(kernels->u->data.S32[kernels->subIndex] == 0 &&
@@ -173,4 +174,14 @@
            kernels->xOrder->data.S32[kernels->subIndex] == 0 &&
            kernels->yOrder->data.S32[kernels->subIndex] == 0);
+
+    psKernel *subKernel = kernels->preCalc->data[kernels->subIndex]; // Kernel to subtract
+    for (int i = 0; i < kernels->subIndex; i++) {
+        psKernel *kernel = kernels->preCalc->data[i]; // Kernel of interest
+        (void)psBinaryOp(kernel->image, kernel->image, "-", subKernel->image);
+    }
+    for (int i = kernels->subIndex + 1; i < num; i++) {
+        psKernel *kernel = kernels->preCalc->data[i]; // Kernel of interest
+        (void)psBinaryOp(kernel->image, kernel->image, "-", subKernel->image);
+    }