OUTPUT: 請問rich black同100k有乜分別?

Process color printing use Cyan, Magenta, Yellow and Black ink.

Printing solid black color can be achieved by putting 100% black ink on paper. However, if you want the black even look punchier, you can add the other 3 process inks on top of black ink to produce more ink density and make the black looks richer on paper. That's why it is call rich black when the appeared black consists of more than just 100 black ink