Render binary data safely in html

render.php

<?php
$data = str_split($data, 72);
$color = '#888';
$placeholder = '.';
$repl = function($m) use (&$color, &$placeholder) {
    $x = str_repeat($placeholder, strlen($m[0]));
    return "<span style=\"background-color:{$color};\">{$x}</span>';
};
foreach($data as &$d) {
    $d = str_replace(['<','>'], ['&lt;','&gt;'], $d);
    $d = preg_replace_callback('/\x00+/', $repl, $d);
    $color = '#f88';
    $d = preg_replace_callback('/[\x01-\x0f]+/', $repl, $d);
    $color = '#aaf';
    $d = preg_replace_callback('/[\x10-\x1f]+/', $repl, $d);
    $color = '#fa0';
    $d = preg_replace_callback('/[\x7f-\xff]+/', $repl, $d);
    $color = '#ccc';
    $d = preg_replace_callback('/[^\x20-\x7f]+/', $repl, $d);
}
$data = implode('<br>', $data);
echo $data;