Sasi,
Start on the front panel and create an Image Display object there first (on palette, Vision >> Image Display). Then you can wire the output of one of your IMAQ Vision function VIs to the terminal of that Image Display and see the image.
The default output of those functions is a typedef that is really only a reference to the image object--useful for stringing VIs together on the block diagram, but not for display purposes. Having only this default behavior available may be a bit of a holdover from earlier versions of IMAQ Vision, where it was impossible to display an image within a VI panel; instead, you always had to call a function to render the image in an external window.
Hope that helps,
John
