Portrait backgrounds are an important component of a portrait. For a background to be successful, it must not compete with the main subject yet support the mood of the portrait. Competing shapes and lines intersecting the center of interest must be avoided. Unless an artistic statement, strong colors tend to distract from the message.If you have a studio in your basement or in a separate room, your background will probably be along the longest uncluttered wall. One unavoidable feature is the line made by the intersection of the wall and the floor. This line often appears in the lower third of the picture, cutting through the portrait without regard to the affect it has on the subject. It can be airbrushed out or otherwise digitally removed but the best solution is to remove it from the room physically. portrait backgrounds is one of the authority sites on this topic.
Many studios rely on hanging a large muslin cloth background on the wall. The benefits of a muslin is that it hides corners and floor lines and can be stored in a bag when not in use. Scenes, however look best when not draped, but stretched fairly tightly across the wall. Solid colors and subtle patterns can be draped loosely or bunched for an artistic effect. Most useful are the subtly blended pastel shades and a solid black. Attached at the ceiling level, they can be long enough to be brought out just short of the camera position for full freedom of posing.
Many portrait studios cater to the popular background choice of white. While pure white does not exist in nature, it is the ultimate expression of non interference in a portrait background. The effect is somewhat remindful of catalog ads but relates well to high key photography and faded out vignettes. A large roll of white paper can be used, but over time is expensive and mars easily. A better solution is a washable painted surface.
This brings us back to the floor line problem. One solution is to build a permanent curved edge into the corner. You take a four foot by four foot piece of three quarter inch plywood and mark it in four squares. Mark the center of each square with a nail and draw a circle to the edges on each square. Jig saw out the center and discard. The four remaining pieces are placed along the wall to support a panel of one quarter inch plywood. Before screwing the panel to the curved supports, sand off the long edge to a sharp bevel. Make sure the flat headed screws are slightly countersunk. Spackle the edges along the wall and floor to appear continuously smooth. Also fill in the screw holes. Paint with one coat of matte white and two coats of washable wall paint. To save the floor from marking, you have an option of using throw rugs on the posing area.
An alternative to a pure white background with curved corners is a fully hand painted 'Rembrandt' background. Done in tones of gray-brown, beige and highlights of blended shades of apple green and wine red, this background can be the default choice for your groups and children portraits. This painted background can be brought out on the floor, gradually shaded to a neutral gray. The curved floor 'invisible horizon' will add much distance and separation to your portraits. With today's digital cameras showing increased depth of field, it is important that the background appear soft and uncluttered.