Index: trunk/psphot/src/psphotGrowthCurve.c
===================================================================
--- trunk/psphot/src/psphotGrowthCurve.c	(revision 6056)
+++ trunk/psphot/src/psphotGrowthCurve.c	(revision 6311)
@@ -15,7 +15,7 @@
     pmModel *modelRef = pmModelAlloc(psf->type);
 
-    // use this image region
-    xc = 0.5*readout->image->numCols;
-    yc = 0.5*readout->image->numRows;
+    // use center of the image 
+    xc = 0.5*(readout->image->numCols + readout->image->col0);
+    yc = 0.5*(readout->image->numRows + readout->image->row0);
     dx = psf->growth->maxRadius + 1;
     dy = psf->growth->maxRadius + 1;