Put the summary of the bug you're having here
What I expected to happen was...:
I expected it to be like I was normally
What actually happened was...:
It went all Black, White and Grey
Steps to Reproduce:
1. Open the menu
2. Go to options
3. Change to peaceful
You have (unintentionally) activated one of the new features of the game: the pencil shader. You likely accidentally pressed the "super secret settings" button, enabling this feature. To disable it simply restart your Minecraft client.