PHP Errors

I had a user of one of my plugins who updated this theme and my plugin stopped working so I installed it to check it out and get a bunch of php errors:

Notice: Undefined index: images_root in /Users/joeanderson/Sites/plugins/ditty-news-ticker/wp-content/themes/atahualpa/header.php on line 42

Notice: Undefined index: full_width_header in /Users/joeanderson/Sites/plugins/ditty-news-ticker/wp-content/themes/atahualpa/header.php on line 64

Notice: Undefined index: full_width_header in /Users/joeanderson/Sites/plugins/ditty-news-ticker/wp-content/themes/atahualpa/header.php on line 82

Notice: Undefined index: full_width_footer in /Users/joeanderson/Sites/plugins/ditty-news-ticker/wp-content/themes/atahualpa/footer.php on line 92

Notice: Undefined index: widget_center_top in /Users/joeanderson/Sites/plugins/ditty-news-ticker/wp-content/themes/atahualpa/index.php on line 11

Notice: Undefined index: widget_center_bottom in /Users/joeanderson/Sites/plugins/ditty-news-ticker/wp-content/themes/atahualpa/index.php on line 51

Notice: Undefined index: full_width_footer in /Users/joeanderson/Sites/plugins/ditty-news-ticker/wp-content/themes/atahualpa/footer.php on line 120

I believe the footer error (the last one) is probably the main cause of the user’s issue as I think it’s causing the wp_footer() function to not fire. I’m guessing these errors would be resolved once I saved some of the theme settings, but for some reason they must be popping up for upgrades as well… Would you be able to add default values for these options to resolve these errors?

Thanks!