igoravl/surround_img_tags_with_figure.php

## surround_img_tags_with_figure.php
<?php

function surround_img_tags_with_figure( $content )
{
    $content = preg_replace(
		'/<p>((<a.+?\>)?<img.*title=\"([^\\"]+)\".*?>(<\/a>)?)<\/p>/',
		'<p><figure>$1<figcaption>$3</figcaption></figure>',
		$content);

    return $content;
}

add_filter( 'the_content', 'surround_img_tags_with_figure', 99 );

?>
	<?php

	function surround_img_tags_with_figure( $content )
	{
	$content = preg_replace(
	'/<p>((<a.+?\>)?<img.title=\"([^\\"]+)\".?>(<\/a>)?)<\/p>/',
	'<p><figure>$1<figcaption>$3</figcaption></figure>',
	$content);

	return $content;
	}

	add_filter( 'the_content', 'surround_img_tags_with_figure', 99 );

	?>