WP_Customize_Header_Image_Setting example

new WP_Customize_Filter_Setting(
                $this,
                'header_image',
                array(
                    'default'        => sprintf( get_theme_support( 'custom-header', 'default-image' ), get_template_directory_uri(), get_stylesheet_directory_uri() ),
                    'theme_supports' => 'custom-header',
                )
            )
        );

        $this->add_setting(
            new WP_Customize_Header_Image_Setting(
                $this,
                'header_image_data',
                array(
                    'theme_supports' => 'custom-header',
                )
            )
        );

        /* * Switch image settings to postMessage when video support is enabled since * it entails that the_custom_header_markup() will be used, and thus selective * refresh can be utilized. */