If you like to upload a custom header image with a taller height in your WordPress P2 theme then you can easily do it by editing your theme’s function file.
Open your P2 theme’s function.php file and add the following code:
/* Custom Header Code */
define(‘HEADER_TEXTCOLOR’, ‘3478E3’);
define(‘HEADER_IMAGE’, ”); // %s is theme dir uri
define(‘HEADER_IMAGE_WIDTH’, 980);
define(‘HEADER_IMAGE_HEIGHT’, 120);
Remember to modify the given code with your own color, image and image’s width-height. –SOURCE