negative colour screen

[skai88]

i am currently on my imac 5.1 intel core 2 duo 2.16ghz. my 2 year old son managed to change my screen into negative color this includes everything from start up picture to screensaver to photo booth to skype etc etc etc. i have tried everything to get my screen back to normal and can't do it hoping you have any idea on how to fix this

 

[MrCheeto]

Press:

Command+Control+Option+8

 

[Warbitrary]

Screen altering preferences like zoom, grayscale, etc. are here:
System Preferences > Universal Access > Seeing

To disable or enable the Universal Access keyboard shortcuts:
System Preferences > Keyboard > Keyboard shortcuts