Photoshop
Filters and Special Effects
Duotones
The actual purpose of duotones is to extend the tonal range of a greyscale image for the printing press. You've probably seen ads or brochures where photos are in a single colour; for example, in shades of blue. This is another use for duotones. Duotones can be part of your design arsenal in Web imagery as well. You can use the same duotone colour on multiple images to create a visual theme for a site. Old black and white photos can be tinted using a sepia duotone. We'll lead you through the basic steps of applying duotones in this lecture.
To use this process, an image must be in Duotone colour mode. Between one and four colours can be used. Since images using duotones are usually intended for printing presses, the colours in the Duotone Options dialog are referred to as inks. Photoshop has four variations for images in Duotone colour mode: monotones, duotones, tritones and quadtones.
A duotone (two-colour) effect is created with black and another colour which combine to tint the tonal range of a greyscale image. Duotones are the most dramatic in that they can be quite saturated with colour, depending on which colour you're working with. When a third or fourth colour is added to the mix (tritones and quadtones) it tends to mute the saturation yet can lead to some subtle but interesting colour effects. Monotones aren't particularly useful since they lack the black ink to add the needed colour depth to a photo. Monotone and duotone effects have been applied to the same image so you can see the difference between them.
Two Rules for Duotone Colour Mode
- Rule #1
- Your image must be in Greyscale colour mode before you can convert it to Duotone mode. If it's not, the Duotone option will be greyed out.
- Rule #2
- Duotone colour mode will affect every layer in your image the same way. Therefore, if you want to try out different duotones (or tritones or quadtones) and compare the results side by side, create duplicate documents of your greyscale image before proceeding.
Practice Exercise: Experimenting with Duotones
- Pick an image for this exercise - either one from this course or one of your own. Select something that has a good tonal range. If you're selecting images from the course, avoid the bird and apple tree images because of their limited tonal range. We're going to use the art_history.jpg in our examples.
- Go to Image > Duplicate and in the Duplicate Image dialog, name this new image duotone.psd. Close the original image.
- Go to Image > Mode > Greyscale. Depending on whether your image has one or more layers, do one of the following:
- Single layer: A message will appear saying, "Discard colour information?" Click the OK button to convert your image to Greyscale mode.
- Multiple layers: A message will appear saying, "Changing modes will affect layer compositing. Merge layers before mode change?" Click the Merge button to merge layers and convert to Greyscale mode.
- Switch to Duotone mode by going to Image > Mode > Duotone. This will open the Duotone Options dialog.
Your dialog will probably display a different colour for Ink 2. All you ready need to concern yourself with in the dialog is the Load button. If the Preview button is enabled, your image should now display the current duotone applied to it.
Duotones, tritones and quadtones use either Pantone or CMYK (Process) inks since they are intended for print use. Not to worry, though; you can convert your image back to RGB mode after you've modified an image in Duotone colour mode.
- Click on the Load button. This opens the Load dialog where you choose whether you want a duotone, tritone or quadtone and select a colour or colours. All of these options are located in a folder called Duotones in the application's Presets folder. In the Duotones folder, there are subfolders for Duotones, Tritones and Quadtones. Here's the complete folder hierarchy:
- Presets
- Duotones
- Duotones
- Grey/Black Duotones
- PANTONE Duotones
- Process Duotones
- Quadtones
- Grey Quadtones
- PANTONE Quadtones
- Process Quadtones
- Tritones
- Grey Tritones
- PANTONE Tritones
- Process Tritones
- Duotones
- Duotones
The Grey options create warm or cool tones in the image without dramatically changing the overall greyscale appearance. The Pantone options use Pantone inks and the Process options use CMYK colours.
- Start in the Duotones > Duotones subfolder and select either a Pantone or Process duotone. Click Load to apply the duotone to your image. The Duotone Options dialog will still be open. We chose cyan bl 2 from the Process Duotones folder for this result:
You'll notice as you navigate through the list of duotones that there are often sequentially numbered colours, like cyan bl 1, cyan bl 2, cyan bl 3, cyan bl 4. The same colour is used in each case but at different strengths. A value of 1 will be the most saturated with colour and a value of 4 will be the least saturated.
- Take several minutes to explore all the folders and try out different duotones, tritones and quadtones. When you find one you really like, click on the OK button in the Duotone Options dialog to close it.
If you change your mind after you've closed the dialog, you can re-open it and select a new colour by going back to Image > Mode > Duotone.
All but a handful of filters are available for images in Duotone mode. You can save directly to Web format from Duotone mode using the Save for Web & Devices dialog. The saved image will be converted to RGB colour automatically. The problem with keeping the image in Duotone mode is that if you decide to add elements to the image, your colour choices are restricted to those contained in the image. So unless you think you'll change your mind about the duotone you applied, it's best to convert the image to RGB mode if other image manipulations are planned.
Here's the old image we worked on earlier with a Process sepia tritone applied to it.
Duotones Summary
- The intended purpose of duotones is to extend the tonal range of a greyscale image that will be printed on a printing press.
- Duotones are created with black and one other colour. Tritones use black and two other colours. Quadtones use black and three other colours. Monotones only use one colour.
- An image must be in Greyscale colour mode before it can be converted to Duotone mode.
- The duotone process uses Pantone or CMYK (Process) inks for the colour component.
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