I'm assuming you're using a Microsoft operating system (XP, 98, etc.). Microsoft Paint will easily edit the size. Just load the image, select "Image", then "Stretch/Skew", set the horizontal and vertical percentages to like 50% and then save. You can adjust the percentage size to your liking, just test them out on your PC screen. Of course there are many more advanced programs out there, but this one's free that comes with your OS. Then upload your new image to your library.