I’ve chosen this brightly colored scene from River Park North in Greenville, North Carolina to demonstrate a technique that I use for producing pseudo duotone High Dynamic Range (HDR) images.
Starting with a realistic version, I used Nik Silver Efex Pro 2 to convert to monochrome with a sepia tone. This process creates a layer in Adobe Photoshop for the Silver Efex Pro version of the image. By adjusting the percentage of fill for the layer to 90%, applying Curves for a little more depth and creating a new layer to add a mild vignette to draw attention away from the corners, I came up with the image below.
Equipment used: Nikon D700 with 20-35mm f/3.5-4.5 lens set at 32mm, f/11, ISO 400. Manfrotto 190XPROB with 486RC2 ball head.

looks like a great place to explore Mark, nicely done!
Thanks, Jim.
I really enjoy your mini tutorials. I do need to pick up a copy of Silver Efex but I’ve been please with Topaz B&W Effects. Love the second image.
Thanks, Edith. I must admit that I still prefer doing monochromes with Photoshop. But, the Nik software is much faster. Haven’t tried the Topaz yet.