define casa_images (ifile, itypes)
{
   variable file_dir, files, obsidstrs, filename;
   variable xoffsets, yoffsets, es, xs, ys;
   variable sel, selsipeak;

   file_dir = "/nfs/spectra/d1/dd/Science/CasA";
   
   files = ["Data/1046/acisf01046N002_E500toE2300evt2.fits",
	    "marx_070301/casa_sim1046.fits"]; 
   
   obsidstrs = ["Real1046", "Sim1046"];
   
   % offsets for the obsids:
   xoffsets = [0.,0.]+4096.0;
   yoffsets = [0.,0.]+4096.0;   
   
   filename = file_dir + "/" + files[ifile];

   % Read in a fits events file:
   % Offset X,Y to nominal location 
   % and convert Energy to keV
   message(" Reading file:  "+filename);
   xs = fits_read_col (filename, "X") - xoffsets[ifile];
   ys = fits_read_col (filename, "Y") - yoffsets[ifile];
   es = fits_read_col (filename, "ENERGY") / 1000.0;
   

   % Define an image size and resolution
   % Don't make any v3d arrays with this resolution!
   v3d_setup(550.0,150);
   
   message(" Select events...");

   % Select events in energy range and spatial range
   sel = where( (abs(xs) < v3d_cube_radius)  and  (abs(ys) < 0.6*v3d_cube_radius) 
		and ( es > 0.50 ) and (es < 2.30) );
   selsipeak = where( (abs(xs) < v3d_cube_radius)  and  (abs(ys) < 0.6*v3d_cube_radius) 
		and ( es > 1.75 ) and ( es < 2.00 ) );

   message("   Number 0.5-2.3 keV : "+string(length(sel)/1000.0)+" x10^3" );
   message("   Number in Si-peak  : "+string(length(selsipeak)/1000.0)+" x10^3" );

   % View the events in simple color-coding by energy
   message(" Creating color image for obsid_"+obsidstrs[ifile]);
   
   % multiple viewing types: 
   variable itype;
   _for itype (0,length(itypes)-1,1)
     {
	% Nominal image...
	v3d_evtimg(xs[sel], ys[sel], es[sel], [0.50,1.60], [1.75,2.00], [2.02,2.30], itypes[itype]);

	% Only show the Si peak range image (green):
	% _Si.png
	% v3d_evtimg(xs[sel], ys[sel], es[sel], , [1.75,2.00], , itypes[itype]);

	% Show the red and blue shifted sides of the He-like Si line:
	% _Silohi.png
	% v3d_evtimg(xs[sel], ys[sel], es[sel], [1.76,1.82], [1.85,1.89], , itypes[itype]);
     }
   
}