Duotone images, as the name suggests, are comprised of only two colours. Technically they can be any two colours, but a classic duotone image is made from a monochrome black/white image; with another highlight colour added to create the two tones.
In this tutorial we’re going to illustrate how to quickly create a duotone image in Photoshop.
Creating the duotone
I’ve found a colour image that I want to use as a starting point; a shot I took in London of the Millennium Bridge. The basic process is to convent the colour image to greyscale, and then to a duotone, so let’s look at how to do that effectively. Below is my original colour image:
You could just go convert to greyscale to create the monochrome version, but this will result in a rather dull image, so it’s better if you do a more creative conversion. There are a number of ways to do this, we’ve already covered how to convert to black and white with the Photoshop Channel Mixer in a separate tutorial.
Here’s my image after a black and white conversion with the Channel Mixer:
I then need to officially convert the image to greyscale, this is done via the menu at the top Image > Mode > Greyscale (shown below).
Then we need to convert the image to a duotone via the same menu Image > Mode > Duotone. This brings up the dialogue box shown below. You need to select duotone from the Type dropdown (there are also options for Tritones and Quadtones too).
To choose your second colour simply click on the colour-box on the right the second ink, this will then bring up the box shown below, you can choose your colour via the regular Photoshop colour picker, or choose a specific colour via the Color Libraries button.
You can also control how the second colour is applied via the curve box, once you click on this the curve dialogue box will display as below.
This is really easy to use, the highlights are on the right, shadows on the left, so just drag and adjust the curve until you get the look that suits your image.
Below are a few different duotones I did using my original image, these are so quick to make it’s easy to create a little range to see what you think works best.
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And that is pretty much it, once you’ve got a version you’re happy with, you can then convert back to a regular RGB image (Image > Mode > RGB Color) so you can save in the file format of your choosing.