What was that novel called?

[Rose Sasha Walker]

It's set somewhere in the future where people have set whole communities which are under strict control- they are drugged to not see colour so racism doesn't exist. The protagonist is a male. We follow him from when he turns 12, which is when there is a celebration and their future careers are decided. Only his name isn't called out in this assembly. He is chosen to become the only person who knows their secrets- that knows colour exists, and knows of another world. He helps lead the people to the outside world- and helps them find colour. He freaks out when he's first able to see the colour red.

I can't remember much more than that.

Thank you =)