Faded photographs are another common problem. Daylight has UV rays which are not good for any image. Over time the vibrance and details fade away and sometimes can’t be fixed.
In this case you can see the edges of the picture have been protected by the frame which gave us a colour reference. This image did take a few hours to fix but it turned out great and Mrs. Grieve is happy to have this and other beautiful pictures of her daughter back to enjoy.