diff -r dee15870206a -r ff1941c85fd3 cylindertransport-web.py
--- a/cylindertransport-web.py	Thu Apr 06 15:41:04 2017 +0200
+++ b/cylindertransport-web.py	Thu Apr 06 16:21:21 2017 +0200
@@ -6,12 +6,14 @@
 
 import cgi, data, json, config
 from cylindertransport import CylinderSpacerCalculator
+import base64
+import cStringIO
 
 # enable debugging
 #import sys
 #sys.stderr = sys.stdout
-#import cgitb
-#cgitb.enable()
+import cgitb
+cgitb.enable()
 
 def do_action(args):
     """
@@ -21,9 +23,14 @@
         cylinders = args.getlist("cylinders[]")
         calc = CylinderSpacerCalculator(cylinders)
         calc.calculate()
+        image = calc.render_image()
+        buffer = cStringIO.StringIO()
+        image.save(buffer, format="PNG")
+        img_str = base64.b64encode(buffer.getvalue())
         print json.dumps({
             "objects": calc.circles,
-            "scale3d": config.SCALE3D
+            "scale3d": config.SCALE3D,
+            "image": img_str
             })
     else:
         print "unknown Action %s" % args["action"].value