pathinfo

<?php
$img = "img/uploads/i/uploads/b0a644eee5e8c47b086d805f7e2ca165.jpg";
$parts = pathinfo($img);

echo '<pre>';
print_r($parts);
echo '</pre>';

?>

Результат выполнения кода:

Array
(
    [dirname] => img/uploads/i/uploads
    [basename] => b0a644eee5e8c47b086d805f7e2ca165.jpg
    [extension] => jpg
    [filename] => b0a644eee5e8c47b086d805f7e2ca165
)