What is the most efficient way to make a full size file out of a small cutout in Photoshop? For example, I have a picture of a group of people and I want to cut out just the face of one of them, but still want to post it on my flickr page as a file with usual resolution, 3000 x 2000 px, not just 30 x 30. I don't mind the obvious loss of quality, blurriness etc. It would be nice to be able to recompose after I cut my frame, so I don't want to delete the rest of my initial file but have it available during postprocessing.
Thanks in advance.