A simple little file to be set at the root of a directory with many images and subdirectories when enables easy viewing of images and navigation of directories.

fileNav.php

<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap.min.css">
<Br>
<?php
function check($array, $input) {
  foreach($array as $value) {
    if(strpos($input, $value) !== false) {
      return true;
  return false;
}

$up = isset($_GET['view']) ? count(explode("/", $_GET['view']))-2 >= 0 ? "<li><a href='?view=" . explode("/", $_GET['view'])[count(explode("/", $_GET['view']))-2] . "'>Up</a></li>" : "<li><a href='./'>Up</a></li>" : "";
$bod = "";
$head = "<ol class='breadcrumb'>" . $up;
$c = 0;
$t = 0;

if (!isset($_GET['view'])) {
  $fins = scandir("./");
  foreach($fins as $i) {
    if (is_dir("./" . $i) && strlen($i) > 2) {
      $head .= "<li><a href='?view=" . $i . "'>" . $i;
    } elseif (is_file("./".$i)) {
      if ($c == 0) { $bod .= '<div class="row">'; }
      if (strpos($i,'.webm') !== false || strpos($i,'.mp4') !== false) {
        $c += 1;
        $t += 1;
        $bod .= "<div class='col-xs-12 col-md-4'><video src='http://localhost/".$i."' style='width:100%' onMouseOver='this.play()' onMouseOut='this.pause()' onclick='this.pause()' loop></video></div>";
      } elseif (check([".png", ".gif", ".jpg", ".jpeg", ".jpe", ".jif", ".jfif", ".jfi", ".jp2", ".j2k", ".jpf", ".jpx", ".jpm", ".mj2"], $i)) { //JPEG, JPEG 2000, GIF, PNG (all supported by GC and FF) 
        $c += 1;
        $t += 1;
        $bod .= '<div class="col-xs-12 col-md-4"><img style="width:100%" src="http://localhost/'.$i.'"></div>';
      }
      if ($c == 3) $bod .= '</div><br>'; $c = 0;
    }
  }
} else {
  if (!is_dir("./" . $_GET['view']))
    die("No directory found");

  $images = scandir("./" . $_GET['view']);
  //shuffle($images);

  foreach($images as $i) {
    if (is_file("./" . $_GET['view'] . "/" . $i)) {
      if ($c == 0) { $bod .= '<div class="row">'; }
      if (strpos($i,'.webm') !== false || strpos($i,'.mp4') !== false) {
        $c += 1;
        $t += 1;
        $bod .= "<div class='col-xs-12 col-md-4'><video src='http://localhost/".$_GET["view"]."/".$i."' style='width:100%' onMouseOver='this.play()' onMouseOut='this.pause()' onclick='this.pause()' loop></video></div>";
      } elseif (check([".png", ".gif", ".jpg", ".jpeg", ".jpe", ".jif", ".jfif", ".jfi", ".jp2", ".j2k", ".jpf", ".jpx", ".jpm", ".mj2"], $i)) { //JPEG, JPEG 2000, GIF, PNG (all supported by GC and FF) 
        $c += 1;
        $t += 1;
        $bod .= '<div class="col-xs-12 col-md-4"><img style="width:100%" src="http://localhost/'.$_GET['view'].'/'.$i.'"></div>';
      }
      if ($c == 3) { $bod .= '</div><br>'; $c = 0; }
    } elseif (is_dir("./" . $_GET['view'] . "/" . $i) && strlen($i) > 2) {
      $head .= "<li><a href='?view=" . $_GET['view'] . "/" . $i . "'>" . $i . "</a></li>";
    }
  }
  $head .= "<li>" . $t . " images in this directory</li>";
}

echo $head . "</ol>";
echo $bod;