Duotones, tritones, and quadtones use spot color inks and multiple passes on a printer. They are expensive to produce because of the separate plates and press washes. Photoshop has a duotone mode. Printing these images on an inkjet printer results in a pseudo-duotone. These can be very lovely images and nearly indistinguishable from a true duo/tri/quadtone.
If all you want to do is produce a toned B&W print, there is no need to convert your image to Duotone mode. You can stay in 16-bits per channel and RGB/CMYK/L*a*b with the TLR B&W Toning action set.
You can use the TLR B&W Toning action set to apply a variety of tones to your monochrome images. Just be sure you have a color image in RGB, CMYK, or L*a*b. The actions apply a gradient map to your image rather than converting to Duotone mode.
The actions for basic tones apply a moderate color tone to the image using a gradient map adjustment layer. You can double-click on the layer and adjust the gradient. You can choose from Blue, Brown, Burgundy, Cyan, Green, magenta, Mauve, Purple, Red, or Yellow.
The actions for sepia tones apply a light to moderate sepia tone to the image using a gradient map adjustment layer.
The actions for color casts apply a light tone to the image using a gradient map adjustment layer. The tones are designed to impose a slight cast to grayscale images or remove a slight cast by applying a neutral gray gradient map. You can choose from Gray Green, Gray Mauve, Cooler Gray, Neutral Gray, or Warmer Gray.
The actions for the traditional tones apply a moderate tone to the image using a gradient map adjustment layer. The tones are designed to simulate traditional toning processes from a chemical darkroom. The available tones include Cyanotype, Gold, Palladium, Platinum, Platinum Palladium, Selenium, Selenium, Selenium Brown, and Silver Gelatin.
The actions for the multi- tones apply a moderate tone to the image using a gradient map adjustment layer. Instead of applying a single tone, a combination of tones are applied to the image. The multi-tone actions include Aqua Gold and Burgundy Gold.
Here's what Len and Joan Weinstock have to say about the TLR B&W Toning action set:
"Your black and white conversion and print toning actions have been extremely helpful in our first attempts at developing a digital monochrome method. We found your platinum tone to be particularly applicable in our latest series. Thanks so much for this assistance."
Below is a before and after example of the action set using a gray green tone.
The B&W toning effects are accomplished with Gradient adjustment layers. That makes them easily adjustable.