In the darkroom toning is done after development.
Typically it's a smelly process (rotten eggs come to mind), and involves
the use of hazardous chemicals. In Photoshop it's ever so easy! The
following picture of Flatford Mill was a favorite subject for painter
To convert a color image to a toned black & white image, add a
Hue/Saturation adjustment layer. Enable the Colorize checkbox and drag
the Hue and Saturation sliders. The Sepia Toning action that comes
with Photoshop sets Hue to 30 and Saturation to 25.