I think (I’m not really 100% sure)…the problem is to do with the resolution of the pictures in books, which is less than an original photographic print would be. As I understand it the scanner picks up the lack of close up detail which isn’t noticable when you just look at the photo in a book with the naked eye.
If you’ve got photoshop or paintshop there are automatic correction things for this kind of effect.
I’d suggest you try scanning a print of photo you took your self to see if it happens with that, that might give you an idea if this is the problem or not.