Just made one myself - an easy way to add a photo to a contact without having to take their real-time picture. However, you still need to have their previously taken picture stored somewhere.
1. Open the contact's picture in Gallery
2. Take out the S-pen.
3. Hold down the S-pen button and draw around the area of the picture that you want to use
Note: draw a bigger area than needed and beware of the yellow square around the face!
4. Dump the selected area in Scapbook
5. Go to contacts and select the needed one.
6. Tap on the place for photo, select "S-Note" from the pop-up menu
7. Select Scrapbook and you'll find the selection
8. Using S-Pen, refine your selection with the rectangle tool that appears (here you'll see why you had to select a bigger area)
9. Click "Done"
Sorry, it does not sound easy with so many steps, but once you try it, you'll find out it IS easy.