I've recently taken up restoring photos. The first photo is nearly 100 years old and using Photoshop Elements 9 I was able to bring out great colour and remove scratches and marks. Who knows, maybe I made the subject look younger lol. You should give it a try, research touch up techniques using your current software. I don't know how good GIMP is but if you don't want to spend money give GIMP a try. The second image shows a photo with missing pieces. Had to use my imagination here as I didn't have the pieces.