reference map output format?

[Sears, Jeremy]

Hi All,
Is it possible to specify the output format for a reference map? If so how?
The documentation indicates that it may be possible however Im having
trouble getting it to work. The default format for the reference map is
.png, Id like to change this to jpg.

This is the php code Im using to generate the reference map:


$map = ms_newMapObj($mapfileloc);

//draw map
$image=$map->draw();
$image_url=$image->saveWebImage();

//draw reference map
$refImage = $map->drawReferenceMap();
$refImageLoc = $refImage->saveWebImage();

I think that I need to include a statement like:

$map->set(imagetype,'image/jpeg'); or somthing... 
A print_r($refimage) indicates that:
>> [imagetype] => png
but Im not sure how to change this. Can someone enlighten me?
Thanks
Jeremy