Answer: My advice to you is to start with a well-lit background. This is assuming you have more than just the ambient lighting the room provides. You will get much better results with several lights on stands, preferably with reflectors. The background needs to be as evenly lit as possible so it will leave no visible outline around your subject once the background is removed in Photoshop. Also, have the subject far enough away from the backdrop so that your subject doesn’t leave a shadow on the green screen. Make sure the subject has no green clothing or accessories on his/her body or it'll make trouble in Photoshop when select the background.

This kind of procedure is commonly called a ‘knockout’, since the foreground image is knocked out of the background. In Photoshop, use the Magic Wand Tool if you have an older version of Photoshop (v4) or the Background Eraser Tool for the newer versions (v6+). Another option to consider is using the Magnetic Lasso Tool. Each of these methods lend themselves to creating selections based on color or contrast. Many other graphics programs have similar tools.

Magic Wand

This tool creates selections based on color and is controlled by the Threshold setting. A selection is created after the user clicks on the canvass with the Magic Wand Tool. The pixels surrounding the area clicked are analyzed and certain shades of color are allowed into the selection, while values outside the Threshold range are ignored. The result is a selection that follows similar shades of color. The bigger the value for Threshold (Options Pallet/Bar), the more variance in color allowed into the selection. Smaller values create selections with a more limited value range. The Magic Wand Tool tends to be imprecise and generally requires touch up work with the help of other selection tools.

Background Eraser

This variant of the Eraser Tool requires that you convert a Background layer (default layer type with limited editability) to a regular editable layer. Simply double-click a Background layer to create a regular layer. A dialogue box will open allowing in you to give the new layer a name, click OK. The Background Eraser tool works by analyzing the color at the crosshairs in the mouse cursor. Colors similar to this target color, which appear inside the brush size are eliminated. Colors not similar to the target color are protected. Keep the crosshairs on the color you want to eliminate, and slightly overlap the brush over the foreground image while you click, hold and drag. The background can easily be erased, as long as the crosshairs does not cross into the foreground image.

Magnetic Lasso

An edge detection technology is built into the Magnetic Lasso Tool. The mouse cursor icon resembles that of the Background Eraser Tool, cross hairs in the middle with a brush around it. Photoshop analyzes the area between the center and outer edge of the mouse cursor, and finds high contrast regions. Normally this does a good job of determining the edge of images. Keep the crosshairs on the edge of the object, and simply trace the image. Photoshop does the rest. For regions that are low contrast, or produce poor results, back up (Backspace) and try clicking where you want the edge to be. The Magnetic Lasso Tool also tends to be imprecise and will require touch up work with the help of another selection tool.

Saving Selections

After the initial selection is made, chances are it will need to be adjusted. Hold the Shift key to add to a selection, or the Alt key to subtract from a selection. Once one of these keys is held, any selection tool can be used to adjust the selection. After you are satisfied with the selection, it would be wise to save the selection. In the Photoshop menu choose Select>Save Selection. Give the selection a name and click OK. When ever you want to reselect the object, simply choose in the Photoshop menu Select>Load Selection.

Removing the background

One way to remove the background would be to invert the selection and delete the background. Often a halo will appear around the image as a result, remnants of the background. To avoid this, the selection can be increased or decreased in size by choosing in the Photoshop menu Select>Modify>Expand or Contract. Another way to further refine the selection is to Feather the selection. The Feather command (found in the Select menu) creates a blended or blurry selection. Next, choose in the Photoshop menu, Select>Inverse. This will reverse the background, allowing you to then press the Delete key. If the result is not what you expected, undo and try again. Experimentation is required in determining the proper values to input into any dialogue box.

New Background

After the original background has been eliminated, find an image that will serve as a surrogate backdrop. Using the Move Tool, drag and drop the background into the target document. Arrange Layers by dragging and dropping so that the layer containing the backdrop is below the image layer you removed the background from. Save the image in an appropriate format, like JPG for e-mails and TIF for printing. Most file formats do not keep layer information so don’t forget to save the Photoshop document. This will allow you to continue to edit the image later, if need be.