Image resize by width only

[eluser]Random dude[/eluser]
Still not adjusting height automatically, here are my settings.

Code:

$config['image_library'] = 'GD2';
        $config['source_image'] = './uploads/' . $swf_folder . '/' . $swf_file_name;
        $config['create_thumb'] = FALSE;
        $config['maintain_ratio'] = TRUE;
        $config['quality'] = "85%";
        $config['new_image'] = './uploads/' . $swf_folder . '/' . $swf_small_file_name;
        $config['width'] = 250;

I think what I need is something like $config['height'] = "AUTO";