$re = '/(?i)^(?=.*logo)(?:https)?:\/\/\S+(?:png|jpe?g|gif|tiff)$/m';
$str = 'https://static.infragistics.com/marketing/Website/home/espn-logo.png
https://static.infragistics.com/marketing/Website/home/mondelez-logo.gif
https://static.infragistics.com/marketing/Website/home/nielsen-logo.jpg
https://static.infragistics.com/marketing/Website/home/united-logo.jpeg
https://static.infragistics.com/marketing/Website/home/merrill-lynch-logo.PNG
https://static.infragistics.com/marketing/Website/home/dell-logo.TIFF
https://static.infragistics.com/marketing/Website/home/intel-logo.gif
https://static.infragistics.com/marketing/Website/home/prudential-logo.png
https://static.infragistics.com/marketing/Website/home/mcdonalds-logo.GIF
https://static.infragistics.com/marketing/Website/home/mcdonalds-alogo.GIF
https://static.infragistics.com/marketing/Website/home/mcdonalds-logos.GIF';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php