Hey I think this will help you:
Enlarge Your Photos Without Sacrificing Quality - PCWorld
The Wrong Way to Enlarge
"You might remember that there's a resizing tool in your photo editing program. In Photoshop Elements, for example, you can choose
Image, Resize, Image Size and specify any size, bigger or smaller than the original photo.
Don't try that, though. Photo editing programs are fairly "dumb," and will just tend to duplicate pixels as needed to make the photo as big as you requested. The result is not pretty; your photo will turn into a blocky, pixelated mess.
In general, you should use your photo editor only to resize a photo smaller, never larger."
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Try SmillaEnlarger
What you need to enlarge a photo is a program designed just for the task. There are a number of commercial programs (and plug-in filters for Photoshop) that will do this. In the past, I've told you about
Genuine Fractals, for example, and PCWorld reviewed the
most recent version. Genuine Fractals uses fractal interpolation--very advanced math--to infer hidden detail when enlarging an image. The result can be Jack Bauer-style image improvements that can dramatically improve the appearance of a print compared to what you'd get with the low-resolution original. The downside? Genuine Fractals is expensive, clocking in at $160"