Printed duotones are actually relatively simple effects to achieve, believe it or not. The trouble is, unless you have a basic understanding of what’s involved, it can feel like a pretty obscure process.
Put simply, duotones are just greyscale images that are printed with two inks rather than one. This is done to give the print result a hue (whether subtle or dramatic) and to achieve greater tonal control and impact. Duotones are traditionally created using black ink and a spot colour. Of course, you can use any two colours that you like, although you’ll need to plan carefully to get the effect you’re after.
Taking a greyscale image and converting it to duotone will give you a pretty subtle result; just a wash of the second colour influencing the midtones.
In Photoshop, choose Image > Mode > Grayscale to convert your image to greys, then choose Image > Mode > Duotone to open the Duotone Options dialog.
You pick your duotone’s second colour here: choose Duotone from the ‘Type’ popup menu, then click the second colour block in this window. If you have arranged to have your job printed using a spot colour (confirm with Unique Cards first!) you can select any Pantone ink. Otherwise, pick one of the Pantone process colours (yellow, cyan or magenta) or click the Picker button to switch to Photoshop’s standard colour picker and set a pure cyan, magenta or yellow colour there. As you choose your colour you’ll be able to see the image change, no need to click OK first.
Notice how anything but the palest inks make the overall image look significantly darker. This is because you’re effectively adding extra ink to the print without balancing things out. In the Duotone Options dialog, click the box to the left of the colour block to open its Curves settings.
Click in the middle of the diagonal line and drag it downwards to the 20 or 25% area. This reduces the amount of this particular ink that will be used for those tones.
If you changed the curves for the black instead you’d get a brighter, more colourful result, weighted more towards the colour ink. Experiment to find the right settings for your image.
You could use a custom CMYK ink mix instead of a single process colour, effectively forcing your duotone to be treated as a tritone or quadtone when printed.
Alternatively, for much greater control, you could make the image a true tritone or quadtone instead – where you use three or even four colours to produce the image. Choose one of those options instead of Duotone from that popup menu and set your inks accordingly. Reduce the curves at different points for each different ink and see how it looks on screen.
You’ll need to save this image as an EPS graphic if you want to use it in a desktop publishing program. Adobe InDesign can use native Photoshop files, but check with Unique Cards & Print for the best format for reproduction.
Photoshop does a pretty good job of showing what the final result will look like, but you’ll need to proof these things carefully to be sure what you’ll get on paper. Ask Unique Cards & Print for information on proofing and for further details about this or other print effects and options.
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