是否有可能获得未包含在链接中的所有图像?

Is it possible to find all images which aren't wrapped in a link?

Example of content:

$content = 'Something <a href="/blog">Blog</a>, lorem ipsum 
<img class="wp-image-1234" src="http://www.website.com/img/image.jpg"> 
dolor sit amet 

<a href="/images"><img class="2344" src="http://www.website.com/img/image.jpg"> Images</a> ipsum dolor lorem 

<img class="aligncenter size-medium wp-image-3201" src="http://www.website.com/wp-content/uploads/2018/07/image-18-300x200.jpg" alt="" srcset="http://www.website.com/wp-content/uploads/2018/07/image-18-300x200.jpg 300w, http://www.website.com/wp-content/uploads/2018/07/image-18-768x512.jpg 768w, http://www.website.com/wp-content/uploads/2018/07/image-18-128x85.jpg 128w, http://www.website.com/wp-content/uploads/2018/07/image-18-375x250.jpg 375w, http://www.website.com/wp-content/uploads/2018/07/image-18.jpg 800w" sizes="(max-width: 300px) 100vw, 300px">

<a href="/image">
<img class="aligncenter size-medium wp-image-3200" src="http://www.website.com/wp-content/uploads/2018/07/image-18-300x200.jpg" alt="" srcset="http://www.website.com/wp-content/uploads/2018/07/image-18-300x200.jpg 300w, http://www.website.com/wp-content/uploads/2018/07/image-18-768x512.jpg 768w, http://www.website.com/wp-content/uploads/2018/07/image-18-128x85.jpg 128w, http://www.website.com/wp-content/uploads/2018/07/image-18-375x250.jpg 375w, http://www.website.com/wp-content/uploads/2018/07/image-18.jpg 800w" sizes="(max-width: 300px) 100vw, 300px">
</a>';

My intention is to manually wrap each image sith a new link, based on ID which I would extract from image class name "wp-image-xxxx" (Wordpress)

PHP language, here is template https://regexr.com/3s0jk

With DOMDocument/DOMXPath:

$doc = DOMDocument::loadHtml($content);
$selector = new DOMXPath($doc);
$query = '//img[not(parent::a)]';

foreach($selector->query($query) as $node) {
    echo $node->getAttribute('src'), PHP_EOL;
}