[Theme: The Frances Wright] Header cropping

Hello, I’m using the Frances Wright template and I want to put a header image without cropping it but it doesn’t let me. I tried looking up the php files but I wasn’t sure what could be the code to remove.

There’s this:

function thefranceswright_header_style()
{
	echo '<style type="text/css">
        #headimg, #lockup {
        	width: 25%;
            min-width: '.HEADER_IMAGE_WIDTH.'px;
        }
        #headimg {
        	margin: 0 auto;
        	width: '.HEADER_IMAGE_WIDTH.'px;
        	height: '.HEADER_IMAGE_HEIGHT.'px;
        	background: url('.get_header_image().');
        }
     ...

And these:

/* Add custom header image globals */
	define( 'NO_HEADER_TEXT', false );

	define( 'HEADER_TEXTCOLOR', '666666' );

	/* Default header image for this theme */
	define( 'HEADER_IMAGE', '%s/assets/images/default_header.png' ); 

	/* Use width & height appropriate for this theme */
	define( 'HEADER_IMAGE_WIDTH', 300 );
	define( 'HEADER_IMAGE_HEIGHT', 300 );

	/* Add theme support for automatic feed links. */
	add_theme_support( 'automatic-feed-links' );

	/* Add theme support for post thumbnails (featured images). */
	add_theme_support( 'post-thumbnails' );

	/* Add theme support for custom headers */
	add_custom_image_header('thefranceswright_header_style', 'thefranceswright_admin_header_style');

I suppose the problem is somewhere here but I’m not sure..!