use MatthiasMullie\PathConverter\Converter;

$from = '/css/imports/icons.css';
$to = '/css/minified.css';

$converter = new Converter($from, $to);
$result = $converter->convert('../../images/icon.jpg');
// $result is now '../images/icon.jpg'

The object constructor accepts 2 paths: the source path your file(s) is/are currently relative to, and the target path to convert to.

$path is the relative file, which is currently relative to $from (in constructor). The return value will be the relative path of this same file, but now relative to $to (in constructor)

Simply add a dependency on matthiasmullie/path-converter to your composer.json file if you use Composer to manage the dependencies of your project:

composer require matthiasmullie/path-converter

Although it's recommended to use Composer, you can actually include these files anyway you want.

PathConverter is MIT licensed.