Simply add a gradient map adjustment layer on top of your image. To create a Duotone, leave the blending mode on "Normal." For color grading, change the blending mode to "Soft Light."
The gradients range from harmonious split toning, vintage and film color grades, popular duotones and two neutral "starting point" gradients. Also included are gradient maps specifically for highlights and shadows.
Use Gradient Maps for one-layer color grading. Put grading map adjustment layer on "soft light" for best results.
Use Gradient Maps to create artistic and graphic duotone images. Keep gradient map layer on the Normal blending mode.