If you're referring to a screen grab of your dvd screen - then yes. Preview the disc/menu - and look above the remote for "copy to clipboarad". Head towards your favourite art package (Paint/ Photoshop etc) and paste.
FWIW... When taking snapshots of mpg2 video, please check the still's aspect &/or frame size after capture & when (re) importing into Vegas/DVDA. It's unfortunately both common & easy to get mangled aspects. If it helps, PowerDVD will approximate the same aspect as a TV, and snapshots can reflect that.