如何在所有情况下从网页获取所有图像？

I am using this script to get all images from a generic external webpage:

$url = ANY URL HERE;
$html = @file_get_contents($url,false,$context);
$dom = new domDocument;
@$dom->loadHTML($html);
$dom->preserveWhiteSpace = false;
$images = $dom->getElementsByTagName('img');

foreach ($images as $image) {
 echo $image->getAttribute('src');
}

But in some cases like this ( where the image is in "rel:image_src" )

<img src="http://example.com/example.png" rel:image_src="http://example.com/dir/me.jpg"  />

it doesn't work.

How can I do ?

Check if the node has an attribute rel:image_src

foreach ($images as $image) {
  if( $image->hasAttribute('rel:image_src') ) {
     echo $image->getAttribute('rel:image_src');
  } else {
     echo $image->getAttribute('src');
  }
}

you could include both:

foreach ($images as $image) {
  echo $image->getAttribute('src');
  echo $image->getAttribute('rel:image_src');
}

If you want the rel:image_src to take precidence, check for the attribute's presence and use it selectively:

$url  = ANY URL HERE;
$html = @file_get_contents($url,false,$context);
$dom  = new domDocument;
@$dom->loadHTML($html);
$dom->preserveWhiteSpace = false;
$images = $dom->getElementsByTagName('img');

foreach ($images as $image) {
  if ($image->hasAttribute('rel:image_src')
  {
    echo $image->getAttribute('rel:image_src');
  }
  else
  {
    echo $image->getAttribute('src');
  }

}