Historically, photographic print toning has used chemical toners like sepia and selenium to make prints with fairly limited colors ranging from brown to purple-reds. With the digital process, however, there are many more color options available together with a near Zone System level of control. For the fainthearted, this digital route is also reversible, so there’s no danger of ruining your perfectly good image file. Subtlety, if you want it, is there in bundles, with no need to produce intimidating Colorvir-like prints, unless hallucinogenic effects are your thing. Digital coloring in CS4 means you can have infinite control over the toning process adding color across the whole image or dropping it in up to ten different tonal sectors. Following is a number of different routes to image toning, starting with the easiest and ending with the more interesting Duotone techniques.

Starting Points

Unlike the darkroom process, you can begin with three different types of image modes, Grayscale, RGB, or CMYK, but you must convert to a desaturated RGB image before you start. If you have a full color image, such as a scan from a color tranny and want to apply an all-over digital tone effect, like selenium, drain the color away by Image > Adjust > Desaturate. This is useful, because the result stays in the RGB color mode.

Using CS4’s Variations Dialog Box

Found under Image > Adjust > Variations, the Variations preview window promptly displays your image surrounded by a range of colored options. In the center box is your image in its current state, surrounded by six color variations, with a lighter and darker version on the right-hand side. At the top right is a slider for increasing or decreasing the increments of change, but best is to start at the Fine end rather than at the Coarse end. Click on any color variation that looks good and watch it affect the center image. You can apply as many adjustments as you like and if you go too far, click on the “original” box (top left) to revert back to your starting point.

Once you are happy with the result, press OK to see the full-sized image. This is by far the easiest way to add image tone, but any subtle changes may be invisible at such a small scale. The final example was created by clicking magenta and cyan.

A weak color image can be transformed radically into a better type of print by toning. This example, shown below, started off as a scan from a color negative (top), which was then desaturated before being toned with CS4’s Duotone functions.

Using the Color Balance Control

Much more sophisticated results can be gained by using CS4’s Color Balance controls. In darkroom terms, this is like printing a black-and-white negative on to color paper using the enlarger’s color filters. Make sure that you have a desaturated RGB image first, then go to Image > Adjust > Color Balance. Here you are faced with familiar Cyan to Red, Magenta to Green, and Yellow to Blue opposites. Move any sliders until you achieve the desired tone effect, but keep the Midtones and Preserve Luminosity buttons checked for best result. You can apply a different color to the highlight and shadow areas, too, by checking their respective buttons and then moving the sliders making a more subtle mix. The example had –22 yellow, with –19 magenta and +27 red applied to the midtones. Avoid saturated colors and be careful about making the image too heavy, as midtones and shadows will clog up during printing.

Using Hue and Saturation

This command gives you the chance to tone with a similar range of colors, having additional control over its saturation or color intensity. Like split-toning photographic prints, using Hue/Saturation can add delicate washes of color to your images. You can start from a full color RGB image, then do an Image > Adjust > Hue/Saturation (6). First, check the Colorize button (bottom right) and observe the dialog box split into three sliders. Your image will have already taken on the default tone. The Hue scale is a linear representation of the color wheel and by sliding along, you can change the overall color.

The Saturation slider dictates the color intensity and is best left on 10–15. The final scale is Lightness, working a bit like a primitive “exposure” adjuster, and is best altered in tiny increments or left alone altogether. Very delicate tones can be applied to your images with this process by moving the Saturation levels lower, allowing you to mimic toners such as selenium. The examples below show three different color variations using the Colorize command.

Duotones

By far, the most sophisticated way to digitally tone an image is to work in the Duotone mode. Duotones are traditionally used in the lithographic printing industry to reproduce high-quality monochrome images, such as those found in Aperture photography books. To mimic the look of an original photographic print, perhaps printed on a warm tone paper or finished with toners, book designers call for additional litho inks to be used. In basic lithographic reproduction, such as a black-ink-only newspaper, grayscale images are printed with one color: standard black ink. Despite 256 levels of gray present in the digital image file, the litho process reduces this down to about 50. The effects of this are disastrous and look very crude. As each additional ink color needs a separate printing plate, adding to the overall cost, quality comes but only at a premium. However, with the introduction of each new color, a further 50 tonal steps are added, edging ever closer to faithfully reproducing that original photographic print.

In many Aperture monographs, additional warm brown and light tan inks are often used to retain the “feel” of the photographers’ work, and part of the book’s higher than average cost can be due to tritone (three ink colors) or quadtone (four ink colors) printing and the complex film separations that need to be made.

Surprisingly, Duotone mode (and tritone and quadtone) digital images can be printed out by most desktop inkjet printers, so the process need not only be restricted to litho output. The most interesting aspect of toning in this way is that you can work with a personal swatch of colors, manipulating each in up to ten different tonal sectors.

Making a Simple Blue Duotone

Start with a grayscale image, then do Image > Image Mode > Duotone. In the Duotone dialog box, black is set as the default first ink color and there will be a blank box next to Ink 2. Clicking this blank box reveals the Color Picker, where you can choose the second color or click on Custom and select a Pantone color, such as blue 279 C. Photoshop immediately updates your image window, (behind the dialog), showing the effect the blue creates. Next, click on the small curve graph to the left of the ink color square. Like the Curves controls, pulling or pushing the straight line will darken or lighten the blue color.

Using the Duotone Curves Dialog Box

If the concept of curves still eludes you, using Duotone curves can make things much clearer. Printing ink is usually expressed in percentage terms, and in the curves dialog, the normal grayscale range of 0–255 is converted to a 0–100% scale. The graph is divided into ten sectors, with each square representing a 10% step in tone. The line is a straight diagonal by default, meaning each original grayscale value is substituted with the same percentage of new color with highlight bottom left and shadow top right. You can manipulate the color by clicking anchor points on the curve and moving them. By pushing the curve into the pink zone, this will darken the color and pulling into the white zone will lighten it. To make things even clearer, there’s a text box to the right, which corresponds to your anchor point, giving a readout of the new color value as you move the curve. If you want to remove an anchor point, just press the delete key. You can leave the curve alone all together, and just type new values in the text box, watch the curve change shape and your image changing color. If you think of these 0–100% values representing ten tonal zones from highlight to shadow, you can see the huge creative scope for manipulation.

Fine Tuning

Most problems using this method occur if you let all inks (colors) run into the shadow areas, giving heavy prints with spreading blacks. The tritone example below was created with three ink colors: black, brown, and tan.

Both black and brown inks were pulled in the midtones to lessen their effect, shown below, but the tan color was pushed further into the highlights, shown below-bottom, to make it more evident. The final result shows a finer distribution of tone than previous methods (Editor's note: this effect is more pronounced in the printed example in the book). If you want to stop the new color reaching the shadow areas, type 60 in the 100% box, watch the curve change shape and that color drop out of the shadows altogether. To make the midtones lighter, type 10 in the 50% box. This way, you decide which tonal sector the color sits in and how bright it is in that area.

Using the Duotone Presets

Photoshop comes with a set of ready-made duo, tritone, and quadtone “recipe” files, which can be loaded for use on your grayscale images. To apply one of these “recipes” to your image, click on the Custom pop-up menu in the Duotones dialog box and select any of the premixed color recipes. There are some excellent examples that can be used to mimic warm, cold, or vintage photographic papers. Most important, the unusual curve shapes in the readymades give you a very good idea of how to control color distribution. This example above was created using a vivid orange for the third color, although you’d never believe it in the final result.

Saving Duotone Recipes

When you arrive at a combination and blend of colors that you like, you can save the recipe as a Duotone settings file. This tiny data file can be saved and stored away for use on future images, and like the hard-won chemical toning techniques, you can preserve your findings and swap them with other users. There are many Duotone recipe files available over the Internet, developed by enthusiasts and posted as shareware.

Making a Cyanotype

You can reproduce this technique by starting with a grayscale image scanned from a negative, print, or object. The example shows a group of fabric and leaves scanned together with a sheet of writing paper, avoiding the need for cutting out. After correcting, do an Image > Adjust > Invert to recreate the negative effect of contact printing. Change the image mode to Duotone, and make a tritone with three blue values.