They may be too large for posting here. Somewhere in the Help section is a post that gives directions for resizing a picture on a PC, and I JUST discovered how to do it tonight on a Mac!
On a Mac, open the picture in Preview. Go to the Tools menu, open it, and choose Resize. When that little window pops up, tell it "Custom" and choose 480 x 640. Works like a charm. I even asked my husband, the Mac genius, how to resize a picture, and he told me we didn't have the software.... I went online and asked, and I found a 4 year old forum with help, and = Bingo!
Hope this helps you!
Melinda