Index: trunk/Ohana/src/opihi/cmd.astro/cdensify.c
===================================================================
--- trunk/Ohana/src/opihi/cmd.astro/cdensify.c	(revision 41340)
+++ trunk/Ohana/src/opihi/cmd.astro/cdensify.c	(revision 41341)
@@ -39,4 +39,11 @@
   }
 
+  int binning = 1;
+  if ((N = get_argument (argc, argv, "-binning"))) {
+    remove_argument (N, &argc, argv);
+    binning = atoi(argv[N]);
+    remove_argument (N, &argc, argv);
+  }
+
   int PSFTYPE = IS_DOT;
   if ((N = get_argument (argc, argv, "-psf"))) {
@@ -80,6 +87,9 @@
   Ymax = graphmode.ymax;
   Ymin = graphmode.ymin;
-  dX = (Xmax - Xmin) / (Xpix - 1);
-  dY = (Ymax - Ymin) / (Ypix - 1);
+
+  // (dX, dY) are the pixel scale of the output image (output pixels / input pixels)
+
+  dX = binning * (Xmax - Xmin) / (Xpix - 1);
+  dY = binning * (Ymax - Ymin) / (Ypix - 1);
 
   CHECKVAL(Xmin);