https://www.electronicgurudev.in/technology/install-extract-filter-in-photoshop-cs5/
Back in Photoshop CS3 and earlier, the Extract filter was a lifesaver when it came to extracting a furry or hairy subject from its background (hence the name). However, Adobe dropped this filter back in Photoshop CS4 in favor of the new—and, in CS5, much improved—Refine Edge dialog box. That said, if you feel you can’t live life without the Extract filter and you still own Photoshop CS3 (or if you copied the filter to Photoshop CS4), you can drag and drop it from the older version of the program into the new one. Here’s how:
Quit Photoshop and locate the Adobe Photoshop CS3 application folder on your hard drive and then find the
Filters➝ExtractPlus.plugin file (it’s named ExtractPlus.8BF on a PC).
Also you can download the same by searching the term – “ download ExtractPlus.8BF” or click on the following URL – http://goo.gl/qnv7G
Drag it to the Filters folder inside the Adobe Photoshop CS5 folder on your hard drive and then launch Photoshop CS5. You should see the Extract filter in the Filter menu from now on.
Once you’ve got it installed, choose Filter➝Extract. In the resulting dialog box, use the Edge Highlighter (it’s automatically selected) to mark the edges of the item you want to isolate. Just place your cursor half on and half off the object’s edge and then trace all the way around the object (a nice, green outline appears). Be careful to surround the area you want to keep completely with the Edge Highlighter.
Next, switch to the Fill tool at the top left of the dialog box (it looks like a paint bucket) and click within the area you want to keep (it will turn purple). When you click the Preview button, Photoshop analyzes the edge you’ve marked and throws away the background. If you’re satisfied with the results, click OK to exit the dialog box. If you’re not, use the Cleanup tool (also on the left side of the dialog box) to fine-tune the edges or Option-click (Alt-click on a PC) the Cancel button (it turns into a Reset button).
This filter is destructive, meaning that Photoshop gets rid of the deleted areas for good. The fix is to duplicate the original layer by pressing -J (Ctrl+J on a PC) and then run the filter on the copy. When the filter has finished processing, load the duplicate layer as a selection and then add a layer mask to the original layer. That way, you can edit the mask if you need to clean up any of the edges.