Added efault value to dimfromroi to prevent errors.

scripts/ih-extract-multi

@@ -10,7 +10,7 @@ parser.add_argument("--inputs", dest="inputs", nargs="+", help="Path to processe
 parser.add_argument("--db", dest="db", help="Path to database to write", required = True)
 parser.add_argument("--createdb", dest="createdb", default=False, action="store_true", help = "Create database file specified by db")
 parser.add_argument("--dimensions", dest="dimensions", default=False, action="store_true", help="Extract dimensions.")
-parser.add_argument("--dimfromroi", dest="dimfromroi", nargs="+", help="Path to roi files for modified dimensions extraction.")
+parser.add_argument("--dimfromroi", dest="dimfromroi", default=[], nargs="+", help="Path to roi files for modified dimensions extraction.")
 parser.add_argument("--pixels", dest="pixels", default=False, action="store_true", help="Extract pixels.")
 parser.add_argument("--colors", dest="colors", default=False, action="store_true", help="Extract color data.")
 parser.add_argument("--channels", dest="channels", default=False, action="store_true", help="Extract channel data.")