Index: /branches/eam_branches/ipp-20110710/psphot/src/psphotModelBackground.c
===================================================================
--- /branches/eam_branches/ipp-20110710/psphot/src/psphotModelBackground.c	(revision 32287)
+++ /branches/eam_branches/ipp-20110710/psphot/src/psphotModelBackground.c	(revision 32288)
@@ -145,4 +145,5 @@
     psMetadataAddPtr(analysis, PS_LIST_TAIL, "PSPHOT.BACKGROUND.BINNING", PS_DATA_UNKNOWN | PS_META_REPLACE, "Background binning", binning);
 
+    psVector *dQ = psVectorAllocEmpty (100, PS_TYPE_F32);
     psF32 **modelData = model->data.F32;
     psF32 **modelStdevData = modelStdev->data.F32;
@@ -216,4 +217,6 @@
                 }
                 modelStdevData[iy][ix] = psStatsGetValue(stats, statsOptionWidth);
+		// fprintf (stderr, "dQ : %f - %f - %f = %f\n", stats->robustLQ, stats->robustMedian, stats->robustUQ, stats->robustUQ + stats->robustLQ - 2*stats->robustMedian);
+		psVectorAppend (dQ, stats->robustUQ + stats->robustLQ - 2*stats->robustMedian);
 
                 // supply sample to plotting routing
@@ -324,7 +327,11 @@
     psLogMsg ("psphot", PS_LOG_WARN, "built background image: %f sec\n", psTimerMark ("psphot.background"));
 
-    psMetadataAddF32(readout->analysis, PS_LIST_TAIL, "SKY_MEAN", PS_META_REPLACE, "sky mean", Value);
+    psStats *statsDQ = psStatsAlloc (PS_STAT_SAMPLE_MEDIAN);
+    psVectorStats (statsDQ, dQ, NULL, NULL, 0);
+
+    psMetadataAddF32(readout->analysis, PS_LIST_TAIL, "SKY_MEAN",  PS_META_REPLACE, "sky mean", Value);
     psMetadataAddF32(readout->analysis, PS_LIST_TAIL, "SKY_STDEV", PS_META_REPLACE, "sky stdev", ValueStdev);
-    psLogMsg ("psphot", PS_LOG_INFO, "image sky : mean %f stdev %f", Value, ValueStdev);
+    psMetadataAddF32(readout->analysis, PS_LIST_TAIL, "SKY_DQ",    PS_META_REPLACE, "sky quartile slope", statsDQ->sampleMedian);
+    psLogMsg ("psphot", PS_LOG_INFO, "image sky : mean %f, stdev %f, dQ %f", Value, ValueStdev, statsDQ->sampleMedian);
 
     // measure image and background stats and save for later output
@@ -334,6 +341,8 @@
                                       PS_STAT_MAX);
     psImageStats (statsBck, model, NULL, 0);
-    psMetadataAddF32 (readout->analysis, PS_LIST_TAIL, "MSKY_MN", PS_META_REPLACE, "sky model mean",          statsBck->sampleMean);
+    psMetadataAddF32 (readout->analysis, PS_LIST_TAIL, "MSKY_MN",  PS_META_REPLACE, "sky model mean",          statsBck->sampleMean);
     psMetadataAddF32 (readout->analysis, PS_LIST_TAIL, "MSKY_SIG", PS_META_REPLACE, "sky model stdev",         statsBck->sampleStdev);
+    psMetadataAddF32 (readout->analysis, PS_LIST_TAIL, "MSKY_DEV", PS_META_REPLACE, "sky stdev",               ValueStdev);
+    psMetadataAddF32 (readout->analysis, PS_LIST_TAIL, "MSKY_DQ",  PS_META_REPLACE, "sky quartile slope",      statsDQ->sampleMedian);
     psMetadataAddF32 (readout->analysis, PS_LIST_TAIL, "MSKY_MAX", PS_META_REPLACE, "sky model maximum value", statsBck->max);
     psMetadataAddF32 (readout->analysis, PS_LIST_TAIL, "MSKY_MIN", PS_META_REPLACE, "sky model minimum value", statsBck->min);
@@ -343,4 +352,7 @@
               statsBck->min, statsBck->sampleMean, statsBck->max, statsBck->sampleStdev);
 
+    psFree(statsDQ);
+    psFree(dQ);
+
     psFree(stats);
     psFree(statsBck);