For transforming images into duotones in CMYK color space
To automatically create duotones in color-managed workflows, Stephen Herron has created collections of duotone profiles that reproduce Adobe Photoshop's standard duotones. A collection of 12 duotone profiles are available free from the Isis Imaging website; another collection of duotone ICC profiles in 24 colors is also available.
Quadtone Profiles: Isis Imaging also offers a Quadtone ICC profile that enables any ICC-aware application to prepare images for output on inksets that feature multiple densities of black inks. (Isis Imaging: www.isisimaging.com)