here's how to re-size by pixels.... at least in the editors I use.(photoshop) You should have some sort of image>resize/size function, Look for the option to resize, you may have the the choice of pixels or inches. Set the size to the pixels you want, that should do the trick. 50x50 is a pretty tiny file, be careful what you choose so that it will be visible without a magnifying glass.

HTH

Irulan