Index: /trunk/ippScripts/scripts/detrend_reject_imfile.pl
===================================================================
--- /trunk/ippScripts/scripts/detrend_reject_imfile.pl	(revision 11501)
+++ /trunk/ippScripts/scripts/detrend_reject_imfile.pl	(revision 11502)
@@ -228,5 +228,8 @@
 }
 my $stdev = sqrt($varianceStats->mean()); # Root-Mean-Square of the imfile stdevs (root mean of variances)
-print "exposure mean $mean, stdev $stdev, mean stdev $meanStdev\n";
+my $exp_sn = 0.0;
+if ($stdev > 0) { $exp_sn = $mean / $stdev; }
+
+print "exposure mean $mean, stdev $stdev, mean stdev $meanStdev, exp s/n: $exp_sn\n";
 
 ## Reject based on the exposure ensemble stats
@@ -263,5 +266,5 @@
 # reject if the signal-to-noise is insufficient
 if ($reject_exp_sn) {
-    if ($mean < $stdev * $reject_exp_sn) {
+    if (abs($mean) < abs($stdev * $reject_exp_sn)) {
 	print "Rejecting exposure based on poor S/N: \n";
 	print "signal: $mean vs noise: $stdev (s/n limit is: $reject_exp_sn)\n";