How To Use Grayscale?

[DRE]

How can I use gray scale on my Mac OSX 10.8.4 or Windows 7 or Windows 8 does anyone know?

All I want to do is view some thumbnails in a picture folder in black and white.

and see what other parts of the computer looks like.

 

[DRE]

NVM found it.

 

[DRE]

I want to make a short cut for this. Hmm.