Tutorial: Extracting Images in Photoshop

Normally, I’m a painter, however now and then I do some graphic design and have to do some photo-manipulation. One of the things that separates a good photo manip from a bad one is how cleanly the image was extracted from the original photo before being inserted into the new one. In Photoshop there are several ways to do this. You can select things painstakingly with the lasso tool. You can carefully erase or mask around the image. Or, if you’re aware of it, you can let Photoshop do most of the work for you.

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So here I have a really lovely image from the incomparable Elandria. The pose is great, the lighting is good, costume and props are spot on. The photo resolution could be a little better, but we’re going to downsize it a little so that won’t matter so much. The only bad thing about this: the background. She’s standing on a picnic table, which would be wonderful if we wanted her to be pointing the way toward lunch, but not so good for a dramatic piece. However, since this is a stock image, we’re going to be cutting her out of there anyway and giving her a much more suitable backdrop to pose so dramatically in. In this case, a beautiful cloudy Scottish countryside from Patronus_Stock.

The first thing you want to do, with the image already open in Photoshop, is find the Extract Filter. I’m not sure why this is classified with the filters, but it is. Simply click on Filters>Extract, which will open up a new and probably unfamiliar window. Now, before we continue, I need to give you some bad news: Your computer is blind. It’s okay, it was born that way, and has come up with a rather complicated system to be able to “see” color. What our eyes perceive as varying shades of red or blue or green, the computer sees as sets of numbers. While we might be able to say “that’s light blue” or “that’s dark blue” the computer has to try to distinguish how similar the numbers are. This can sometimes cause difficulties when selecting things with the magnetic lasso, and it can also cause problems here, too, so it’s better to be aware of it.On the left hand side of this window are our tools. The first button is your edge highlighter, the second is a fill paintcan. You won’t need the eyedropper tool much, so I tend to ignore it, but you will need the one beneath it later. The bottom two are your magnifying glass and move tools, which you’ll want to use quite a bit as we go.On the right hand side you’ve got your settings. Make sure you’ve got the Highlight and the Fill colors set to different colors (blue and green here). They’re not actually going to be coloring your image, so you can set them to whatever colors you like. If your image has a lot of well defined areas (like this one), you’ll want to check the box next to “smart highlighting.” This tells the computer to automatically follow defined edges of “color.”

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Pick a portion of your image and zoom in. Set the highlighter tool size so that if you place it on the edge of your image, it overlaps into the part you want to keep by a few pixels, and overlaps onto the background a few pixels. Then begin tracing around the edge of the part of the image you want to extract. As long as you stick fairly close to the edge, the smart highlighting will follow along it without you having to be too exact.

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Things will get a little funny around soft edges, like hair. When you’re working around the hair, color over any loose fringes you want to keep. Use the eraser tool to clean up any places where your brush got a little wonky.

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Once you’ve outlined everything you want to keep (make sure to get those weird little holes and gaps, too, like the spaces between the flag and the pole, or the hole between her arm and her body), use the fill tool to color in the part you want to keep. Basically, what you’re telling the computer with the green highlighter is: This is the edge of the image, keep any pixels that match the colors closest to the fill and get rid of the rest. With the fill tool you’re telling it “I want to keep this.”Click Preview. What you should see is your image “cut out” of it’s background. Now, remember what I said about the computer getting confused? It’s going to sometimes get rid of some pixels you wanted, and leave some you didn’t. That’s where the clean up brushes come in.

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The top clean up brush (not sure if it has a name) can make the pixels either transparent or opaque. To “erase” some of those messy edges, simply paint over them. However, if you want to make an edge come back (like the bottom of her sleeve), hold down the Alt key (option on a Mac) while painting to make it visible again. Go back around the edge of your image and clean up any problem areas. For messy areas, like her hair, use a smaller brush and “paint” in lines that are opaque that follow the flow of her hair.When you’re finished the extracted image should look much cleaner in your preview window. If everything is good, hit okay to accept the extraction and go back to your main Photoshop window.

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In Photoshop, you’ll see that the computer has deleted all of the background image, leaving you with a nice (hopefully cleanly cut out) figure which can now be dropped into its new home. If you’re not sure how clean your edges are, make a new layer underneath the extracted image, and fill it with a flat color. You might still need to erase a few crumbs, but for the most part, Photoshop has done the hard work for you. Now when you move the image into it’s new background, your edges should be clear, and you’ll still retain some of those hard to cut out areas like hair or blurred edges. Final image, after I’ve applied filters and effects, and painted over a couple of spots):Close up:Credits:
Stand Before the Banner used with permission from Elandria/Caustic-Stock at DeviantArt.com
St. Abb’s Head used with permission from Patronus_Stock at DeviantArt.comTutorials are copyrighted as well. Please do not repost or reprint without my permission. Contact me at mercuralis@bynkii.com for information.