"thumb_format" => '',
function PHPThumbQueryStr()
{
global $PHPTHUMB_CONFIG, $modx;
@require_once($modx->config["base_path"].PHPTHUMB_PATH."phpThumb.config.php");
$path_info = pathinfo($this->current["source"]["src"]);
$format = strtolower($path_info["extension"]);
$format = ($format == "jpeg") ? "jpg" : $format;
$format = ($this->current["config"]["thumb_format"] != "") ? $this->current["config"]["thumb_format"] : $format;
$this->current["phpthumb_parms"]["f"] = $format;
if ($this->current["process_mode"] == "thumb")
{
$prefix = "thumb_";
if ($format == "jpg")
$this->current["phpthumb_parms"]["q"] = $this->current["config"]["thumb_quality"];
$phpthumb_parms_name = "thumb_phpthumb_parms";
}
else
{
if ($format == "jpg")
$this->current["phpthumb_parms"]["q"] = $this->current["config"]["big_quality"];
$phpthumb_parms_name = "big_phpthumb_parms";
}
$this->current["phpthumb_parms"]["sia"] = $prefix.basename($this->current["source"]["src"], $path_info["extension"]) . $format;
$format = ($format == "jpg") ? "jpeg" : $format;
how can i archive to keep the original size of the big image, that shows up in the Lightbox?

Try to use www.domain to domain rewrite rule in .htaccess.
i did that, just wanted to check if i’ve missed something in the configuration...Could you post this rewrite rule here and tell me where to place it in .htaccess?
# for the opposite domain.com -> www.domain.com use the following
# >>> DO NOT USE BOTH THE ABOVE AND BELOW <<<
#
RewriteCond %{HTTP_HOST} .
RewriteCond %{HTTP_HOST} !^www\.yourdomain\.com [NC]
RewriteRule (.*) http://www.yourdomain.com/$1 [R=301,L]