Black & White with Color
You’ve seen this Black & White – Color effect just about everywhere. One of the reasons why is it doesn’t take much time to do in Photoshop.
In this case I want to have the croissant be colored so I’ll just erase the top black and white layer where the croissant is. I used an eraser that was fairly soft in order to get it to look natural. If you’re looking for more of a flushed color look rather than black and white it’s simple to do! Just adjust the opacity of the top layer to your liking.
Comprehensive Guide to Color in Photoshop – Colorize a Black and White Photo