Keying Out Backgrounds in Photoshop
This article will explain how to remove or 'key' green screens or blue screens or remove plain color backgrounds in Photoshop (works with versions 5, 6, 7/CS, CS 2 and CS 3). You might want to do this kind of thing after using your brand-new DIY Greenscreen you just made...
Videographers often use green screens to film people and put backgrounds in that were either too hard to create in the real world or were too hard for the actors/talent to travel to. In photography, 'green screening' can be very useful for many different purposes. Not only does it make it easy for someone to change the scenic background behind a person, it also can help to make distinctive portrait backgrounds or 'cut out' an object that you would like to be able to manipulate easier.
(Quick Note: This guide is simply explaining one Photoshop technique (among many) for removing solid color backgrounds. To acquire a good, evenly-lit background is a completely different topic (and one which I don't have time to discuss here).
The easiest and most effective method for 'keying' (removing) any plain color (green, blue, or any other color) background in Photoshop (as long as the subject has none of that color in his/her clothing or makeup!) is to use the 'Color Range...' command, located in the 'Select' menu. (You could also remove the background by using the 'magic wand' or drawing with the pen or lasso tool around the subject, but if you have a good, solid color background (even with less-than-stellar lighting), it's much easier to use the Color Range command.
There are also many other ways to 'knock out' the green or blue (or other colors, for that matter!) that can be easier or harder, depending on your source photo. You could use the Magic Wand, using special plugins, using a Channel mixer adjustment layer, or mask your image in quick mask mode. The biggest advantage to using the Color Range command is that you can easily set up an Action for batch processing photos, and your selection can be used for many /sites/lifeisaprayer.com/files/articles/photography.
For more discussion and information, I'd highly recommend one of the following books:
- Greenscreen Made Easy: Keying and Compositing Techniques for Indie Filmmakers
- The Greenscreen Handbook: Real-World Production Techniques
The step-by-step instructions below work with Adobe Photoshop CS, but should be similar (if not exactly the same with other version of Photoshop, including CS2-5, 5.0, 6.0 and 7.0).
- Open the photo you would like to remove the green screen from in Photoshop.
- Select 'Color Range...' from the 'Select' menu.
- After the Color Range dialog box comes up, click on the eyedropper tool, drag the 'Fuzziness' slider to about 30, check the 'Invert' checkbox, choose 'Grayscale' from the 'Selection Preview' popup and make sure the 'Selection' radio button is pressed.
- With the eyedropper tool, click in the green area of the image (either on the main canvas or in the 'Color Range' dialog. You should see much of the green area as white, and the rest of the image (which will be selected) black. If there are still areas (because of non-uniform lighting) of the green screen which are not white, hold down the Shift key and click on them with the eyedropper until all of the green area is selected.
- This selection should work pretty well, but if there are still pixels here and there that are white, you can lower the Fuzziness until it's easier to click on the areas. Also, you can hold down the shift key and click and drag your mouse across an area to select many points at once, instead of clicking for each point. To select with even greater accuracy, you can zoom in by pressing 'Command' - '+' (Mac) or 'Control' - '+' (Windows).
- Once you're satisfied with your selection, click 'OK'.
- You should see the object you are trying to select selected. If there are any problem areas (i.e. you see scrolling ants in areas inside or outside your selection that shouldn't be selected), use the lasso tool (hold down Shift or Option (Mac)/Control (Windows) to add to or subtract from the selection) to make your selection perfect.
- Now you are ready to remove the green or blue screen. Make sure you're working with the proper layer, and, if you are on the 'Background' layer, double-click it and click 'OK' to make it into a normal layer, then select 'Inverse' from the 'Select' menu to reverse the selection.
- Now press the 'delete' button or select 'Clear' from the 'Edit' menu to remove the selection.
- You will find that the edges of your object/person may have a slight 'halo' around them. Clean up the edges by choosing 'Layer>Matting>Remove White Matte' or by choosing 'Layer>Matting>Defringe...'; usually 1-3 pixels will do the trick.
- Now you can put any background you would like behind your cut-out object. Just make sure you place the background into a layer behind your current layer. (A good way to make quick-and-dirty portrait backgrounds is to choose a couple of colors in the color-pickers and to select 'Filter>Render>Clouds' then play around with noise, blurriness, etc.).
Tips for Improving Color Keys
- Try to have well and uniformly lit backgrounds. You should try to use at least two lights for a green or blue screen background, to make sure it is evenly lit.
- When taking pictures with a digital camera, make sure it is set to its highest setting; for higher-end cameras, use the RAW setting (which uses no compression and makes the green background much more uniform). For lower-quality cameras, set the JPEG compression to the maximum quality.
- When filming, try to use the best quality tape and camera you can; DV compression is harder to work with when chromakeying, so try to use uncompressed footage if possible.
- Experiment with the different settings—especially the 'Fuzziness'—in Photoshop; for some images, it might be easier to have the 'Fuzziness' at '0' to select parts of the image, then raise the amount after you are satisfied with your selection. Photoshop's amazing array of abilities make it a wonderful tool to experiment with.
Here are some other articles on Life is a Prayer.com that you may be interested in reading. Also, be sure to check out Jeff Geerling's blog.