Wordpress - Add Custom Image Size to Admin Area

gistfile1.txt

//////////////////////////////////
// Add new image size to WordPress
//////////////////////////////////
add_image_size( 'catalog', 490, 340, array( 'center', 'top' ) ); // Hard crop center top
// make the new size available in the media library (and image element etc.)
add_filter( 'image_size_names_choose', 'my_custom_images' );
function my_custom_images( $sizes ) {
    return array_merge( $sizes, array(
        'catalog' => __( 'Catalogue Image' ),
    ) );
}