1.Create first a backup file for the picture. Better if you'll create another folder for your original images.
2.After backing up your original image files, open the image that you want to extract. Click Filter > Extract. It will open a new window with your image.
3.Use the Highlight tool in it. For example you want to extract a picture of a lady from a picture of group of ladies, using the extract tool, trace the portion that you want to extract. you can use the Zoom options to carefully draw the bondaries of the image (or rather to carefully highlight the image) that you want to extract. The hand tool will also be very useful in going to places in the image.
4.Be sure that when you choose the image that you want to extract, the highlighted portion of the image is enclosed. Which means that your point of start will also be the end. In short, just highlight the image that you want to extract.
5.Then activate the Fill tool, by pressing G. Be sure that the bucket icon is placed inside the image that you highlighted. Click it, then the image that you want to extract will turn blue which means that you have chosen the highlighted portion. Click Preview.
6.In the Preview, you will see that the image was not finely extracted. So you will have to use several tools; Edge Highlight, Eraser, Edge Touchup and Cleanup. The Edge Touchup restores the subject edges, while Cleanup removes the background elements.
7.If you are already satisfied with the cleanness of the image, press OK. And there you have it, an extracted image. You can copy it and paste it to another group of pictures or set another picture as its new background.