issue with get_custom_header returing 0 for height/width

when useing get_custom_header the array returns the height and width as 0px

in my functions.php i have

$headerDefaults = array(
	'default-image' => get_template_directory_uri() . '/images/header.png',
	'random-default'         => false,
	'flex-height'            => false,
	'flex-width'             => true,
	'uploads'                => true,
		'width'         => 450,
		'height'        => 150,
);

in my header.php i have

<img src="<?php header_image(); ?>" height="<?php echo get_custom_header()->height; ?>" width="<?php echo get_custom_header()->width; ?>" alt="" />
the array returns

stdClass Object
(
    [url] => http://democustom.globalclassroomportal.com/wp-content/uploads/sites/9/2014/07/demo-custom-logo1.png
    [thumbnail_url] => http://www.msite.com/wp-content/uploads/sites/9/2014/07/demo-custom-logo1.png
    [width] => 0
    [height] => 0
    [attachment_id] => 231
)