Duotones Tutorial Author - Man1c M0g (http://forums.biorust.com/member.php?userid=1)

Contrary to popular opinion, those 'classy' black & white photos taken for glossy magazines and media shoots are rarely ever purely black & white (i.e. monotone).  Even the best industry-standard printers have great difficulty printing more than 50 distinct shades of grey.  To enhance this greatly and improve underlying tonal quality, a second color is often added, making the image two-color (or 'Duotone').

This tutorial details the deceptively simple yet very configurable way in which Photoshop handles images with restricted configurable tonality.   The results are subtle, yet very impressive even before they are printed.
 

Step 1: Open up a stock image in Photoshop of any size and/or format. If you have a darkly-colored source image you may want to spend a few minutes playing with the contrast/brightness or levels to improve the overall color clarity. Discard all your color information by selecting Image > Mode > Greyscale from the main menu.  You should now be able to choose Image > Mode > Duotone from the same menu.

Step 2: At this stage you have complete creative freedom.  In my example I decided to select two inks for my image (i.e. Duotone), with the colors shown opposite.  If you click on the swatches there are a great deal of inks to choose from, but the usual combinations involve a black and one other color.  If you click on the curve next to the color swatch you can open up a curve for fine adjustment of the ink application.

Step 3: It should be borne in mind, of course, that Photoshop comes with a good-sized library of duotones for you to load - just click on the 'load...' button and check them out. Once you are finished with the color selection, create a new adjustment layer from the main menu via Layer > New Adjustment Layer > Curves. You can use this curve to adjust the overall tonality of your image.  Understanding curves themselves is a more advanced subject and best left to a separate tutorial.

Step 4: And there we have it - a high quality duotone image created in a few simple steps. This should not, of course, be the end of your experimentation. Deceptively simple, the duotone dialog offers countless permutations, and even allows the creation of TriTone & QuadTone images.   These are rarely used inside the printing industry,  but the effects can be extremely interesting and well worth the added effort.  Have fun experimenting!