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

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

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

//4、取src
preg_match('/<img.+src=\"?(.+.(jpg|gif|bmp|bnp|png))\"?.+>/i',$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/2017020716154162.jpg")
print preg_replace('/(<img.+src=\"?.+)(images\/)(.+.(jpg|gif|bmp|bnp|png)\"?.+>)/i',"\${1}uc/images/\${3}",$str);
echo "

//2、将src="/uploads/images/20100516000.jpg"替换为src="/uploads/uc/images/2017020716154162.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);
?>