From small to Big! This is my bread and butter.
I love making really small images printable at really large sizes. I mean really large. This image started out as a 35mm slide that was scanned by the museum curators. I took the resulting digital file and made it wall size.
There are many techniques used to do this. Some people use specialized fractal software with crazy algorithms and fancy schmalzy math. I like to do it digi-manually with Photoshop, like we did in the old days. Here the technique involves sizing the images up slowly with smaller increments of resolution. Photoshop's math skills are not too shabby either, but I find that sizing up this way provides a great opportunity to study the image and see where it might need some help later in the process.