Index: trunk/ppStack/src/ppStackMatch.c
===================================================================
--- trunk/ppStack/src/ppStackMatch.c	(revision 25447)
+++ trunk/ppStack/src/ppStackMatch.c	(revision 25467)
@@ -15,5 +15,5 @@
 #define SOURCE_MASK (PM_SOURCE_MODE_FAIL | PM_SOURCE_MODE_DEFECT | PM_SOURCE_MODE_SATURATED | \
                      PM_SOURCE_MODE_CR_LIMIT | PM_SOURCE_MODE_EXT_LIMIT) // Mask to apply to input sources
-#define FAINT_SOURCE_FRAC 1.0e-4         // Set minimum flux to this fraction of faintest source flux
+#define NOISE_FRACTION 0.01             // Set minimum flux to this fraction of noise
 #define COVAR_FRAC 0.01                 // Truncation fraction for covariance matrix
 
@@ -319,4 +319,19 @@
             pmReadout *fake = pmReadoutAlloc(NULL); // Fake readout with target PSF
 
+            psStats *bg = psStatsAlloc(PS_STAT_ROBUST_STDEV); // Statistics for background
+            psRandom *rng = psRandomAlloc(PS_RANDOM_TAUS); // Random number generator
+            if (!psImageBackground(bg, NULL, readout->image, readout->mask, maskVal | maskBad, rng)) {
+                psError(PS_ERR_UNKNOWN, false, "Can't measure background for image.");
+                psFree(fake);
+                psFree(optWidths);
+                psFree(conv);
+                psFree(bg);
+                psFree(rng);
+                return false;
+            }
+            float minFlux = NOISE_FRACTION * bg->robustStdev; // Minimum flux level for fake image
+            psFree(rng);
+            psFree(bg);
+
             // For the sake of stamps, remove nearby sources
             psArray *stampSources = stackSourcesFilter(options->sourceLists->data[index],
@@ -325,5 +340,5 @@
             if (!pmReadoutFakeFromSources(fake, readout->image->numCols, readout->image->numRows,
                                           stampSources, SOURCE_MASK, NULL, NULL, options->psf,
-                                          NAN, footprint + size, false, true)) {
+                                          minFlux, footprint + size, false, true)) {
                 psError(PS_ERR_UNKNOWN, false, "Unable to generate fake image with target PSF.");
                 psFree(fake);
@@ -371,5 +386,5 @@
                                                                PM_SUBTRACTION_ANALYSIS_KERNEL); // Conv kernel
             if (kernel) {
-                if (!pmSubtractionMatchPrecalc(conv, NULL, readout, fake, readout->analysis,
+                if (!pmSubtractionMatchPrecalc(NULL, conv, fake, readout, readout->analysis,
                                                stride, sysError, maskVal, maskBad, maskPoor,
                                                poorFrac, badFrac)) {
@@ -385,10 +400,10 @@
                 }
             } else {
-                if (!pmSubtractionMatch(conv, NULL, readout, fake, footprint, stride, regionSize, spacing,
+                if (!pmSubtractionMatch(NULL, conv, fake, readout, footprint, stride, regionSize, spacing,
                                         threshold, stampSources, stampsName, type, size, order, widths,
                                         orders, inner, ringsOrder, binning, penalty,
                                         optimum, optWidths, optOrder, optThresh, iter, rej, sysError,
                                         maskVal, maskBad, maskPoor, poorFrac, badFrac,
-                                        PM_SUBTRACTION_MODE_1)) {
+                                        PM_SUBTRACTION_MODE_2)) {
                     psError(PS_ERR_UNKNOWN, false, "Unable to match images.");
                     psFree(fake);