If the photo was taken by a Carnival photographer, it is protected by copyright laws and most reputable places - Walgreens, Wal-mart, Target, Wolf, etc. - will not make a copy for you if they realize the photo is professional since the law prevents them from doing so.
I agree with Mr October... buy a scanner! If not, you just take a photo OF the photo with a digital camera.
Don't use a flash, you'll get glare! A great way to do this is to shoot it outside in the sunlight but have someone hold up a piece of white fabric to diffuse the direct sunlight. You'll get a great digital copy that way.
The cruise lines are wise to people scanning the pictures that they take. Some cruise lines are encoding the pictures. When you scan the pictures they may have CARNIVAL across the picture in big block letters.