knihovna GD

<?php
$velkost_x = 200;
$velkost_y = 75;

$text = mt_rand(100000, 999999);

$miesto_na_znak = $velkost_x / (strlen( $text ) +1 );
$obrazok = imagecreatetruecolor( $velkost_x, $velkost_y );

$pozadie = imagecolorallocate ( $obrazok, 255, 255, 255 );
$okraj = imagecolorallocate ( $obrazok, 128, 128, 128 );
$farby[] = imagecolorallocate ( $obrazok, 128, 64, 192 );
$farby[] = imagecolorallocate ( $obrazok, 192, 64, 128 );
$farby[] = imagecolorallocate ( $obrazok, 108, 190, 64 );

imagefilledrectangle( $obrazok, 1, 1, $velkost_x - 2,
                      $velkost_y - 2, $pozadie);
imagerectangle( $obrazok, 0, 0, $velkost_x - 1, $velkost_y - 1, $okraj );

for ( $i = 0; $i < strlen($text); $i++) {
$farba = $farby[$i % count( $farby)];
imagettftext (
$obrazok,
28 + rand(0, 8),
-20 + rand(0, 40),
( $i +0.3 ) * $miesto_na_znak,
50 + rand( 0, 10 ),
$farba,
'arial.ttf',
$text{$i}
); //31 riadok
}

imageantialias( $obrazok, true );  //34 riadok

for ( $i = 0; $i < 1000; $i++)
{
$x1 = rand( 5, $velkost_x -5 );
$y1 = rand(5, $velkost_y -5 );
$x2 = $x1 - 4 + rand( 0, 8 );
$y2 = $y1 - 4 + rand( 0, 8 );
imageline( $obrazok, $x1, $y1, $x2, $y1,
$farby[rand(0, count($farby) - 1 ) ]
);
}

header('Content-Type: image/png');
imagepng($obrazok);
?>