Digital Outback Photo's Guide to Uprezzing Digital Images
Digital Outback Photo have published a comprehensive tutorial on upsizing digital images using Photoshop CS.
“Whenever the topic of interpolating digital files for the purpose of large print output is mentioned, you usually hear arguments break out over which method is the “best” one. The most popular methods of interpolation mentioned are usually some form of stepped bi-cubic interpolation in imaging programs such as Photoshop, or the use of programs specifically dedicated to accomplishing this task like the Genuine Fractals interpolation product or Q-Image?s printing program. While most of these traditional methods work fairly well, they all have their shortcomings. Over time I have tested virtually every method available…”