// Add featured image to posts/pages.
add_action( 'genesis_entry_content', 'spi_do_featured_image', 1 );
function spi_do_featured_image() {

    // if we are not on a single Post page, abort.
    if ( ! is_singular( 'post' ) ) {
        return;
    }

	$show_image = get_theme_mod( 'spi_single_image_setting', true );

	$img = genesis_get_image( array(
		'format'  => 'html',
		'size'    => genesis_get_option( 'image_size' ),
		'context' => 'archive',
		'attr'    => genesis_parse_attr( 'entry-image', array ( 'alt' => get_the_title() ) ),
	) );

	if ( ! empty( $img ) && ( true === $show_image ) ) {
		echo $img;
	}

}