Image resize

<?php

///////////////////////////////////////////////////////
// FlowerBoy paveiksleliu mazinimo varikliukas v.1.2 //
///////////////////////////////////////////////////////
    $filename = realpath($_SERVER['DOCUMENT_ROOT'].DIRECTORY_SEPARATOR.$_GET['f']);

    if (isset ($_GET['p'])) {
        $plotis = $_GET['p'];
    }
    if (isset ($_GET['a'])) {
        $aukstis = $_GET['a'];
    }
    if (isset ($_GET['max'])) {
        $dydis = getimagesize($filename);
        if ($dydis['0'] <= $dydis['1']) {
            $aukstis = $_GET['max'];
        }
        if ($dydis['0'] > $dydis['1']) {
            $plotis = $_GET['max'];
        }
    }
    if (isset ($_GET['min'])) {
        $dydis = getimagesize($filename);
        if ($dydis['0'] >= $dydis['1']) {
            $aukstis = $_GET['min'];
        }
        if ($dydis['0'] < $dydis['1']) {
            $plotis = $_GET['min'];
        }
    }

    header("Content-type: image/jpeg");
    $source = imagecreatefromjpeg($filename);

    if ($plotis != "") {
        $thumbX = $plotis;
        $imageX = imagesx($source);
        $imageY = imagesy($source);
        $thumbY = (int)(($thumbX * $imageY) / $imageX);
    }

    if ($aukstis != "") {
        $thumbY = $aukstis;
        $imageX = imagesx($source);
        $imageY = imagesy($source);
        $thumbX = (int)(($thumbY * $imageX) / $imageY);
    }
    $dest = imagecreatetruecolor($thumbX, $thumbY);

    imagecopyresampled($dest, $source, 0, 0, 0, 0, $thumbX, $thumbY, $imageX, $imageY);

    imagejpeg($dest, "", "100");

    imagedestroy($dest);
    imagedestroy($source);
?>