<?php
/*PHP正则提取图片img标记中的任意属性*/
$str = '<center><img src="/uploads/images/20100516000.jpg" height="120" width="120"><br />PHP正则提取或更改图片img标记中的任意属性</center>';

//1、取整个图片代码
preg_match('/<\s*img\s+[^>]*?src\s*=\s*(\'|\")(.*?)\\1[^>]*?\/?\s*>/i',$str,$match);
echo $match[0];

//2、取width
preg_match('/<img.+(width=\"?\d*\"?).+>/i',$str,$match);
echo $match[1];

//3、取height
preg_match('/<img.+(height=\"?\d*\"?).+>/i',$str,$match);
echo $match[1];

//4、取src
preg_match('/<img.+src=\"?(.+\.(jpg|gif|bmp|bnp|png))\"?.+>/i',$str,$match);
echo $match[1];

/*PHP正则替换图片img标记中的任意属性*/
//1、将src="/uploads/images/20100516000.jpg"替换为src="/uploads/uc/images/20100516000.jpg")
print preg_replace('/(<img.+src=\"?.+)(images\/)(.+\.(jpg|gif|bmp|bnp|png)\"?.+>)/i',"\${1}uc/images/\${3}",$str);
echo "<hr/>";

//2、将src="/uploads/images/20100516000.jpg"替换为src="/uploads/uc/images/20100516000.jpg",并省去宽和高
print preg_replace('/(<img).+(src=\"?.+)images\/(.+\.(jpg|gif|bmp|bnp|png)\"?).+>/i',"\${1} \${2}uc/images/\${3}>",$str);
?>

$str = '<p><img src="/zb_users/upload/202003/o4jrwvh01xv.png" /></p><p><img src="/Home/images/404.jpg" style="" title="404.jpg"/></p><p><img src="/zb_users/upload/202003/o4jrwvh01xv.png" style="" title="1529561322214.png"/></p><p><br/></p>';
$preg = '/<img.*?src=[\"|\']?(.*?)[\"|\']?\s.*?>/i';//匹配img标签的正则表达式
preg_match_all($preg, $str, $allImg);//这里匹配所有的img
echo '<pre>';
print_r($allImg);

(  
[0] => Array  
(  
  [0] => <img src="/zb_users/upload/202003/o4jrwvh01xv.png" />  
  [1] => <img src="/Home/images/404.jpg" style="" title="404.jpg"/>  
  [2] => <img src="/zb_users/upload/202003/o4jrwvh01xv.png" style="" title="1529561322214.png"/>  
)  
[1] => Array  
(  
  [0] => /upload/20180621/1529561322214.png  
  [1] => /Home/images/404.jpg  
  [2] => /upload/20180621/1529561322214.png  
)  
)