functions

<?php

// Register a custom image size for Singular Featured images
add_image_size( 'singular-featured-thumb', 800, 250, true );

add_action( 'genesis_before_entry', 'sk_display_featured_image' );
function sk_display_featured_image() {
	if ( ! is_singular( array( 'post', 'page' ) ) ) {
		return;
	}
	if ( ! has_post_thumbnail() ) {
		return;
	}
	// Display featured image above content
	echo '<div class="singular-featured-image">';
		genesis_image( array( 'size' => 'singular-featured-thumb' ) );
	echo '</div>';
}