(PHP) Pegar BMP Facebook

<?php

$usuario = $_GET['user'];

$imagem = "http://graph.facebook.com/$usuario/picture";
$arquivo = "tmp.bmp";

$imagem_source = imagecreatefromjpeg($imagem);

imagebmp($imagem_source, $arquivo);


// @site: http://www.codingforums.com/archive/index.php/t-157438.html
// @author: kokjj87
function imagebmp( &$im, $filename = "") {
    if (!$im) return false;
    $w = imagesx($im);
    $h = imagesy($im);
    $result = '';
    if (!imageistruecolor($im)) {
        $tmp = imagecreatetruecolor($w, $h);
        imagecopy($tmp, $im, 0, 0, 0, 0, $w, $h);
        imagedestroy($im);
        $im = & $tmp;
    }
    $biBPLine = $w * 2;
    $biStride = ($biBPLine + 3) & ~3;
    $biSizeImage = $biStride * $h;
    $bfOffBits = 66;
    $bfSize = $bfOffBits + $biSizeImage;
    $result .= substr('BM', 0, 2);
    $result .= pack('VvvV', $bfSize, 0, 0, $bfOffBits);
    $result .= pack('VVVvvVVVVVV', 40, $w, '-'.$h, 1, 16, 3, $biSizeImage, 0, 0, 0, 0);
    $numpad = $biStride - $biBPLine;
    //for ($y = $h - 1; $y >= 0; --$y) {
    $result .= pack('VVV', 63488, 2016, 31);
    for ($y = 0; $y < $h; ++$y) {
        for ($x = 0; $x < $w; ++$x) {
            $rgb = imagecolorat($im, $x, $y);
            $r24 = ($rgb >> 16) & 0xFF;
            $g24 = ($rgb >> 8) & 0xFF;
            $b24 = $rgb & 0xFF;
            $col = ((($r24 >> 3) << 11) | (($g24 >> 2) << 5) | ($b24 >> 3));
            $result .= pack('v', $col);
        }
        for ($i = 0; $i < $numpad; ++$i)
        $result .= pack('C', 0);
    }
    if ($filename == "") {} else {
        echo $result;
    }

    return true;
}

?>