http://manuals.info.apple.com/enUS/iPod_touch_iOS4.1_UserGuide.pdf
If there is no setting for tis, then try the basics troubleshooting from the manual:
Restart.
Reset.
Restore.
ALL YOU HAVE TO DO IS THIS: SELECT SETTINGS> SELECT ACCESSIBILITY> AND MAKE SURE YOUR WHITE ON BLACK IS SET TO OFF>>>>>>PROBLEM SOLVED............... YOU DO NOT HAVE TO RESET ALL SETTINGS, BC YOU PROBABLY WILL HAVE TO THEN GO BACK AND SET UP EVERYTHING THE WAY YOU HAD IT!!! I HAVE SENSATIVE YES AND LOOKING AT THE WHITE BACKGROUND WITH BLACK WRITTING HURTS , SO I TURNED MINE ON SO IT WOULD APPEAR A BLACK BACKGROUND WITH WHITE WRITTING... I HAD NO PICS UPLOADED AT THIS POINT, WHEN I SYNCED HOWEVER MY PICS ALSO LOOKED THIS X RAY TYPE. WHEN I WENT BACK AND TURNED IT TO OFF, MY PROBLEM SOLVED.. SO NOW WHEN I WANT TO LOOK AT OR SHOW MY PICS I SIMPLY DO THIS SO THAT I CAN HAVE BEST OF BOTH WORLDS. AND WHEN JUST LISTNING TO MY TUNES OR RADIO STREME I DONT HAVE OT STRAIN MY EYES!
My wife had had her ipod touch for one day
THANK YOU....ONCE IN THE ACCCESSIBILITY MENU JUST MAKE SURE TO HAVE THE WHITE AND BLACK SET TO OFF THATS IT!!!!!!
Pictures Look Like Xrays