There is no real way to add detail to a print, so as you enlarge it to print, the detail gets worse. There are some tricks that help. A program like adobe photoshop can resize pictures, and there is an old trick of upsizing the file 10% at a time, rather than in one big step. Sometimes the results are surprisingly good. There is a program called Qimage that also helps enlarge and print- no miracles but it does a good job. It is about $50, but there is a free trail available
