Get aspect ratio from width and height of image (PHP or JS)

Question

I can\'t believe I can\'t find the formula for this. I am using a PHP script called SLIR to resize images. The script asks to specify an aspect ratio for cropping. I\'d like

Answer 1

to get the aspect ratio just simplify the width and height like a fraction for example:

1024      4
----  =  ---
768       3

the php code:

function gcd($a, $b)
{
    if ($a == 0 || $b == 0)
        return abs( max(abs($a), abs($b)) );

    $r = $a % $b;
    return ($r != 0) ?
        gcd($b, $r) :
        abs($b);
}

  $gcd=gcd(1024,768);

  echo "Aspect ratio = ". (1024/$gcd) . ":" . (768/$gcd);