existe un plugin del photoshop para realizar aumentos sin muchas perdidas, se llama genuine fractals:

Lizard Tech
Genuine Fractals 3.0

Create resolution-independent images from any size file, and display full-screen, full-color, interactive images on the web with this third-party plug-in. Compatible with Photoshop 6.0 through CS as well as Adobe Photoshop Elements 1.0 or later.

Espero que te sirva....