[UPDATE]BG image

If possible I want to be able to add a BG image in the viewport on perspective view. This is so that I could easily get my reference images when I am modelling.

You could use the [obj mode] "Plane > Create with Image"

well, I want to see image even if I am rotating. if I use a plane it would not follow when I rotate.

I use Floaty (http://www.polycount.com/forum/showthread.php?t=99709) for this kind of stuff. It overlays an image on screen and has a click-through mode. Very handy.

I use Floaty (http://www.polycount.com/forum/showthread.php?t=99709) for this kind of stuff. It overlays an image on screen and has a click-through mode. Very handy.

Thanks, I shall try that:)

EDIT: I tried it, I find it useful. Thanks.