Personally, I got interested in Photoshop when I realized that it could pluck a person out of a photo and then paste him/her onto a totally new background. To this day there are many requests from friends and family who want to do something similar with their photos. So I will be showing you a few techniques to get it done using Photoshop.
Photoshop has the excellent “Extract” filter built especially for such tasks. Photoshop CS4 however, no longer features the Extract filter. So we will first look at how to use the extract tool to pull off the maneuver, then briefly see how you can enable the extract filter in CS4 or use an alternative to the Extract filter. Let’s get working straight away, shall we?
Change the Background of a Photo with The Extract Filter
If you have pre-CS4 version of Photoshop, you can find the Extract filter under the Filter menu. The Extract filter is very useful to cut out or extract a person/object from the photo and then use it on another photo to change the background of the original photo. The tool is very simple to use. Although it opens a giant dialog box there is really no need to be intimidated by it.
First off, go ahead and check the Smart highlighter box right away. Now choose the highlighter tool and draw around the object you want to extract. Make sure you cover the edges, this means that the highlight stroke should roughly lie half on the object you want to extract and half on the background. You don’t have to be precise or want a Wacom tablet. Photoshop will help you along. Somewhat like this:
You can change the brush size of the highlighter for greater precision in corners and smaller areas. Then choose the fill tool from the extract filter toolbar and click once inside the area you want to keep. Hit the preview button and you will be shown what the final image will look like once extract finishes its work. Click OK if the results seem close to what you are looking for, or else you can start over once again.
Duplicate the layer before starting the extract filter. That way, you still have the original image when extract finishes. Now Ctrl + Click on the extracted layer’s thumbnail to load it as a selection. You can now use Select > Refine Edges to improve the selection and hence the extract. Once done hit Ctrl + C and then Ctrl + V to get the extracted-refined object on its own layer.
The Extract Filter in CS4
As I mentioned earlier, the extract filter is no longer present in Photoshop CS4, the latest offering from Adobe. You can simply copy and paste the ExtractPlus.8BF file from your CS3 installation’s Plug-ins/Filters/ folder to the corresponding folder in CS4 install directory. Oh, you can also download it from Adobe’s site if you don’t have a CS3 installation handy. My Bad!
When you fire up Photoshop the next time, you will see the extract command under the Filter menu. You can now use it as detailed above.
Alternatives to Extract Filter
There are always more than one way to achieve similar results in Photoshop. So if you would like to ditch the extract filter altogether you can use the improved quick selection tool. It does a pretty good job of detecting edges. In case it goes wrong, you can always add to (Shift) and subtract from (Alt) the selection. As an added advantage, it gives you a selection you can easily refine, so you wouldn’t have to work extra to get the selection as we did in the expert tip above.
You can also use the freeware InstantMask to mask out a person or object from any photo. It uses a slightly different approach that reminds one of the commercial plug-in Mask Pro from OnOne software but the results vary hugely.
Here is the finished result using the extract tool. Just added a background and some text!
Keep in mind that there is an algorithm doing the processing behind what seems like magic. The application has no idea who or what the object is in the photograph. You get best results when there is good contrast between the object and the background. That is one of the reason people shoot against a green or blue screen because then you can get excellent contrast in the green/blue channel and creating a mask to extract an object is super easy.
Have you attempted the task of changing the background of a photo before? How did you do it?