Add a modern sepia tone to your photos. In this tutorial, you'll learn how to add a sepia tone specifically to the highlights or shadows of an image.
Open a photo you would like to edit. Or, you may use the photo used in this tutorial (from iStockPhoto).

Duplicate the layer (Layer> Duplicate Layer or Ctrl+J). The sepia tone will be applied to the new top layer.

This page will teach you how to add a sepia tone. If you already know how to do this, simply activate the top layer and apply your desired sepia tone effect and skip to the next page. If you would like to learn how to create a basic sepia tone, continue below:
With the top layer selected, use the Hue/Saturation tool to apply the following properties:
Colorize: Checked
Hue: 25
Saturation: 25
Lightness: 0

Use the Variations tool (Image> Adjustments> Variations) to customize the sepia tone. Simply click on the thumbnail of the image that's closest to the effect you would like until you've reached your desired sepia tone. If you make a mistake and want to start over, simply hold the Alt key and press the Reset button (The Cancel button should turn into the Reset button).
