<?php
    $dir = scandir("images/");
    $i = 0;
    foreach($dir as $key => $file){
        echo "<a href='images/{$file}'><img src='images/{$file}' style="max-width:200px;max-height:200px;padding:10px;" /></a>";
        $i++;
        if($i%3==0){
            echo "<br />";
        }
    }
?>