Split Toning in Photoshop

As an alternative to pure black and white you can use Split Toning in Photoshop. In this example you can see that the black has a blue tint, and the white has beige tint. Split toning with two colours is also called Duotone.

First convert your image to black and white. This is not a prerequisite.

Then add an Adjustment Layer called Gradient Map. Click in the field marked with a green arrow and your Gradient Editor opens.

In the Gradient Editor, set the four points marked with red arrows.

The leftmost point already exists, but must be set to black (#000000).

The second point you have to create and set to 30% (shown). Click in the blue field to select your colour (#45475d).

The third point you create and place at 68%, then select your beige (#afa18d).

The rightmost point already exists, but must be set to white (#fcfcfc).

Press OK and your split toning is applied.