Tinting with Duotone, Tritones, and Quadtones
In earlier Trudie Ann tutorials, I talked about some of the more common ways to tint a B&W using Adjustment layers, split-toning with Camera Raw, and even using a Channel Mixer adjustment layer. From the stone age of Photoshop comes colorizing with the Duotone Mode. Duotones are used in print jobs to blend two or more spot colors, one per printing plate, making it possible to give the illusion of more complex color while only using two inks. Since you pay by the number of plates used on the press, duotoning is a way to save costs. In Photoshop jargon, Duotone Mode also covers using one ink that isn’t Black (Monotone), or three inks (Tritone), and even four inks (Quadtone). Although these were expected to be spot colors used for printing, they don’t have to be. You can use Duotone mode to tint an image that is going to be output as an RGB image on your inkjet printer.
Because of the way Duotones work, I recommend creating a flattened duplicate of your image in a new file before converting. Then convert to 8 bit mode, next Image> Mode> Grayscale, and finally Image> Mode> Duotone. Because Duotones aren’t adjustment layers or Smart Filters, unless you work on your file in Duotone mode, you won’t be able to re-edit it. However, while you are in Duotone mode, simply choose Image> Mode> Duotone again to make any changes you want. When you exit the dialog, History will update to say Duotone Options.
Once you open the Duotone dialog, you can get a head start with a Preset, choose how many colors you want to work with (up to four), click on the color swatches to add or change colors, and click on the Curves thumbnail beside each swatch to apply more or less of the color to the tonal range.
The Duotone dialog expects you to apply the darkest color at the top, and the lightest color at the bottom of the stack. Grab hold of a color’s curve at top right and pull it down to keep that color out of the darks. Raise the bottom left point up to add more of a color to the lights, and pull the middle of the curve down to add more color to midtones, or up to remove it from the midtones. Following the expected order makes it easier to anticipate which color will affect which tone. You can, however, edit any curve any way you like.
Since you’re telling Photoshop how much total ink to use in any given tonal region, you’ll quickly see that you’re affecting both tone and color. By adjusting the curves for each color, you adjust the image values at the same time. Duotone Mode is one of those features that’s a lot easier to use than to explain. Once you get in there and start tugging on the curve with a strong dark and a light bright color, you’ll see how the curves for each color work to both add color and contrast to your image. It’s not that different from setting the balance slider in Camera Raw’s Split Tone feature, except you’re adjusting the blend and the brightness more precisely, as well as potentially for four colors. While your document remains in Duotone Mode, you can also add a few types of adjustment layers to modify the tones in the image further.
If you Save the result as a preset while in the Duotone dialog, you can easily Load it for future images. To save the entire document in Duotone Mode, choose Photoshop EPS with 8bit TIFF in the Save As dialog.
When you’re happy with your duotone, drag it into the original document while holding down the Shift key to make it align perfectly with the original image. Remember that once you’ve converted back to RGB, you’ve committed the duotone and won’t be able to edit it again in the Duotone dialog. However, if you edited the image on a duplicate layer, you’ve protected your original file.
By now, you should be getting the idea that there are more ways to color a cat in Photoshop than seems necessary, but each method has its strength. Duotones for RGB files are more a legacy method than commonly used nowadays, but they still provide a way to do the job with a tremendous amount of control by taking advantage of the precision Curves offers, particularly when you start creating Tritones and Quadtones.