WordPressのカスタムヘッダー(custom header)登録サンプルです。

wp-class-custom-header-setup.php

<?php
/**
 * カスタム
 *
 * @package   InfoTown
 * @author    Hiroshi Sawai <info@info-town.jp>
 * @copyright Hiroshi Sawai
 */
class MyTheme_SetUp {
	/**
	 * Add custom header.
	 *
	 * @since 1.0
	 */
	function register_custom_header() {
		$args = array(
			'width'              => 1140,
			'height'             => 330,
			'header-text'        => true,
			'default-text-color' => '333333',
			'default-image'      => esc_url( get_stylesheet_directory_uri() . '/images/default.jpg' ),
			'random-default'     => false,
		);
		$args = apply_filters( 'custom_header_args', $args );
		if ( function_exists( 'get_custom_header' ) ) {
			add_theme_support( 'custom-header', $args );
		} else {
			define( 'NO_HEADER_TEXT', true );
			define( 'HEADER_TEXTCOLOR', $args['default-text-color'] );
			define( 'HEADER_IMAGE', $args['default-image'] );
			define( 'HEADER_IMAGE_WIDTH', $args['width'] );
			define( 'HEADER_IMAGE_HEIGHT', $args['height'] );
			$args['wp-head-callback'];
			$args['admin-head-callback'];
			add_theme_support( 'custom-background', $args );
		}
	}
}

wp-setup.php

<?php
// Support custom header.
$setup = new MyTheme_SetUp();
add_action( 'after_setup_theme', array($setup, 'register_custom_header' ));