Not Quite so Seamless
Many portrait photographers have been in the situation where a model or subject does something spontaneous, it may look good, funny, or in some cases may actually be a 'money shot'. Unfortunately, you may not be in the perfect position to capture the shot as you would like.
Seamless paper had some great advantages, and comes in several sizes. It is important though to keep your subject as well as you the photographer with the boundaries of the paper. In some cases, like above, the photographer can capture the edge of the paper. There are a couple of solutions here. One is to ask your subject to repeat the same pose, which may or may not work out with some of the spontaneous moment lost. One could possibly crop, but as in the case above this would mean cutting off some of the subjects fingers and hand. Of course there are some time intensive compositing techniques one could use, but lets keep this simple.
Sample the backdrop along the edge of the paper that you wish to extend. Then with your paintbrush paint along the border to extend the back drop (you will want to use a large fairly hard brush). At this point, it may look ideal, since there most likely will be a seam. Despite your best sampling, the color may not match as well as you have liked. You could resort to the healing brush or clone brush. Either may (or may not) get the result that you like.
If your image still is not where you would like it..
You may find that your background is practically uniform at this point without that nasty seam and possibly any mild color shift may have resolved.
- Give it a shot, see what you think!