如何仅删除图像宽度和高度，而不是iframe？ 代码包括在内

The code I'm currently using in my wordpress functions file is this:

function remove_width_attribute( $html ) {
   $html = preg_replace( '/(width|height)=("|\')\d*(|px)("|\')\s/', "", $html );
   return $html;
}
add_filter( 'the_content', 'remove_width_attribute', 10 );

The problem here is that it targets iframes too, so how would I rewrite the regex to say images only?

I would just use non capturing groups to search for the img tag before the other statements, something like

(?:img.*)(width|height ?= ?['"].*['"])

Which you can see working here: http://regex101.com/r/mI1bD5.

Note that this fails in a lot of simple cases (iframe on the same line as an img tag for example), but it should push you in the right direction.

Thanks Trevor for helpful suggestion. Here's my revised expression that does a little better, but still not quite there. (?:<img.*){1}((width|height)=['"]\d*['"]) (?:.*\/>|>){1}