WordPress/wp-content/themes/twentyfourteen/image.php

<?php
/**
 * The template for displaying image attachments.
 *
 * @package WordPress
 * @subpackage Twenty_Fourteen
 */

get_header();
?>

<div id="primary" class="content-area image-attachment">
	<div id="content" class="site-content full-width" role="main">

	<?php while ( have_posts() ) : the_post(); ?>

		<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
			<header class="entry-header">
				<h1 class="entry-title"><?php the_title(); ?></h1>

				<div class="entry-meta">
					<?php $metadata = wp_get_attachment_metadata(); ?>

					<span class="entry-date"><time class="entry-date" datetime="<?php echo esc_attr( get_the_date( 'c' ) ); ?>"><?php echo esc_html( get_the_date() ); ?></time></span>

					<span class="full-size-link"><a href="<?php echo wp_get_attachment_url(); ?>" title="Link to full-size image"><?php echo $metadata['width']; ?> &times; <?php echo $metadata['height']; ?></a></span>

					<span class="parent-post-link"><a href="<?php echo get_permalink( $post->post_parent ); ?>" title="Return to <?php echo esc_attr( get_the_title( $post->post_parent ) ); ?>" rel="gallery"><?php echo get_the_title( $post->post_parent ); ?></a></span>
					<?php edit_post_link( __( 'Edit', 'twentyfourteen' ), '<span class="edit-link">', '</span>' ); ?>
				</div><!-- .entry-meta -->
			</header><!-- .entry-header -->

			<div class="entry-content">

				<div class="entry-attachment">
					<div class="attachment">
						<?php
							/**
							 * Grab the IDs of all the image attachments in a gallery so we can get the URL of the next adjacent image in a gallery,
							 * or the first image (if we're looking at the last image in a gallery), or, in a gallery of one, just the link to that image file
							 */
							$attachments = array_values( get_children( array(
								'post_parent'    => $post->post_parent,
								'post_status'    => 'inherit',
								'post_type'      => 'attachment',
								'post_mime_type' => 'image',
								'order'          => 'ASC',
								'orderby'        => 'menu_order ID'
							) ) );
							foreach ( $attachments as $k => $attachment ) {
								if ( $attachment->ID == $post->ID )
									break;
							}
							$k++;
							// If there is more than 1 attachment in a gallery
							if ( count( $attachments ) > 1 ) {
								if ( isset( $attachments[ $k ] ) )
									// get the URL of the next image attachment
									$next_attachment_url = get_attachment_link( $attachments[ $k ]->ID );
								else
									// or get the URL of the first image attachment
									$next_attachment_url = get_attachment_link( $attachments[ 0 ]->ID );
							} else {
								// or, if there's only 1 image, get the URL of the image
								$next_attachment_url = wp_get_attachment_url();
							}
						?>

						<a href="<?php echo $next_attachment_url; ?>" title="<?php echo esc_attr( get_the_title() ); ?>" rel="attachment"><?php
							$attachment_size = apply_filters( 'twentyfourteen_attachment_size', array( 1200, 1200 ) ); // Filterable image size.
							echo wp_get_attachment_image( $post->ID, $attachment_size );
						?></a>
					</div><!-- .attachment -->

					<?php if ( ! empty( $post->post_excerpt ) ) : ?>
					<div class="entry-caption">
						<?php the_excerpt(); ?>
					</div><!-- .entry-caption -->
					<?php endif; ?>
				</div><!-- .entry-attachment -->

				<?php the_content(); ?>
				<?php
					wp_link_pages( array(
						'before'      => '<div class="page-links"><span class="page-links-title">' . __( 'Pages:', 'twentyfourteen' ) . '</span>',
						'after'       => '</div>',
						'link_before' => '<span>',
						'link_after'  => '</span>'
					) );
				?>
			</div><!-- .entry-content -->

			<footer class="entry-meta">
				<?php if ( comments_open() && pings_open() ) : // Comments and trackbacks open ?>
					<?php printf( __( '<a class="comment-link" href="#respond" title="Post a comment">Post a comment</a> or leave a trackback: <a class="trackback-link" href="%s" title="Trackback URL for your post" rel="trackback">Trackback URL</a>.', 'twentyfourteen' ), get_trackback_url() ); ?>
				<?php elseif ( ! comments_open() && pings_open() ) : // Only trackbacks open ?>
					<?php printf( __( 'Comments are closed, but you can leave a trackback: <a class="trackback-link" href="%s" title="Trackback URL for your post" rel="trackback">Trackback URL</a>.', 'twentyfourteen' ), get_trackback_url() ); ?>
				<?php elseif ( comments_open() && ! pings_open() ) : // Only comments open ?>
					<?php _e( 'Trackbacks are closed, but you can <a class="comment-link" href="#respond" title="Post a comment">post a comment</a>.', 'twentyfourteen' ); ?>
				<?php elseif ( ! comments_open() && ! pings_open() ) : // Comments and trackbacks closed ?>
					<?php _e( 'Both comments and trackbacks are currently closed.', 'twentyfourteen' ); ?>
				<?php endif; ?>
			</footer><!-- .entry-meta -->
		</article><!-- #post-<?php the_ID(); ?> -->

		<nav id="image-navigation" class="site-navigation">
			<?php previous_image_link( false, __( '<div class="previous-image">Previous Image</div>', 'twentyfourteen' ) ); ?>
			<?php next_image_link( false, __( '<div class="next-image">Next Image</div>', 'twentyfourteen' ) ); ?>
		</nav><!-- #image-navigation -->

		<?php comments_template(); ?>

	<?php endwhile; // end of the loop. ?>

	</div><!-- #content .site-content -->
</div><!-- #primary .content-area .image-attachment -->

<?php get_sidebar(); ?>

<?php get_footer(); ?>