The Hidden Power of Photoshop CS: Chapter 2: Color Separations. Pt. 1. By Sybex | 6 | WebReference

The Hidden Power of Photoshop CS: Chapter 2: Color Separations. Pt. 1. By Sybex | 6

The Hidden Power of Photoshop CS: Chapter 2: Color Separations. Pt. 1

Manual Duotones

Creating duotones manually is something you will want to do to achieve ultimate control over the duotone result and better understand the application of colors. Working in RGB allows you to create color ink components (also called “plates” or “color plates”) using more intuitive light processes while defining spot color without compromising it as a spot channel or CMYK equivalent.

To create duotones manually, you will use existing image tone along with some tricks that we’ve seen hints of in both using curves and in making RGB separations. If your original image is an RGB image, you should convert to grayscale (see the previous sections on converting to grayscale for these options). Curves are used to adjust the tone for the separate inks, and RGB preview techniques are used to look at the result of combining inks. When the preview looks the way you want, you can create separations that can be used to print duotones at home or to your printing service as grayscale image plates. Here are the steps involved in the manual process:

1. Open an image that is Grayscale mode, or turn a color image to grayscale by the methods described earlier in this chapter. Be sure the image tone is corrected—you won’t want to do this afterward—and be sure the image is flattened. See the sample image used in Figure 2.17.

2. Change the mode of the image to RGB. RGB mode will allow you to preview colors.

Figure 2.17 This western scene (wagontrain.tif on the CD) can garner some additional authenticity by using a sepia tone.

3. Decide on the colors to use for the duotone effect. In this example, to create something of a sepia tone, let’s use black and an RGB value close to Pantone 472 (RGB: 255, 155, 125).

4. Add a new layer, fill with white, and call the layer Composite. This layer will be used

as a background to display the duotone result.

5. Duplicate the background to create a new layer, and drag it to the top of the layer stack.

6. Rename the new layer Duotone 1. You may want to identify the layer by the color/tone you expect to apply (e.g., Black 6), by generic names like “Duotone 1,” by RGB values, or by Pantone color names.

7. Change the mode of the layer to Multiply. Multiply mode will ensure that the layer content acts like ink on paper, darkening the composite layer.

8. Add a new Solid Color layer (Layer ‘ New Fill Layer ‘ Solid Color), group it with the Duotone 1 layer, and choose the darker color selected in step 3. Change the mode of the layer to Screen, and name the layer Color 1. Screen mode will convert the tone to a representation of the selected color.

9. Activate the Duotone 1 layer.

Figure 2.18 This curve for the darker Duotone 1 ink was used to increase contrast in the grassy midtones.

10. Add a Curve adjustment layer by choosing Layer ‘ New Adjustment Layer ‘ Curves. Enable the option Use Previous Layer To Create Clipping Mask in the New Layer dialog box so that the adjustment affects only the Duotone 1 layer. In the example, use the curve shown in Figure 2.18.

11. Repeat steps 5 through 10 to add the second duotone color. Name the layers you create Duotone 2 and Color 2. Figure 2.19 shows the curve used for the fill color and how the layer stack should look.

Figure 2.19 The curve for the lighter Duotone 2 color concentrates on influencing the highlights and midtones.

The result of the steps can be seen in the color section.

For the layer order, the curves should be directly above the duotone layer they are adjusting, between the tone and the color. If you put the curve above the color, your curves will influence the color as well as the tone. Grouping the curves ensures that the curve influences only the duotone color where it is applied. If you want more spot colors, repeat steps 5 through 10.

You can use a gradient bar as part of the process to judge the quality of the gradient you are creating when combining the colors. To do this, add a blank layer above one of the duotone layers (Duotone 1), make a selection where you want the bar to appear, and fill the selection with a gradient from white to black (left to right, or right to left). Duplicate the layer containing the gradient and move it to just above the other tone layer (Duotone 2). Duplicating the layer ensures the gradients are identical. The gradient should appear relatively smooth and even after placement, unless you are using the duotone for some type of image correction or special effect.

I have provided a sample gradient bar action with the Hidden Power Tools on the CD. You can set up a duotone in layers using the Duotone Layer Setup action, and then add a gradient bar without a lot of fuss by clicking Duotone Preview. Removing Duotone Preview will delete the gradient bar layers.

You can use this to check how smooth your mixing is or to help while developing curves for application. This action will work for any duotone set up as described using Duotone 1 and Duotone 2 as the naming convention. When you are done with the preview, just delete the bar layers.

With the result on screen, you have several options for generating prints. You will handle this differently depending on what you want to accomplish. In the simplest scenario, you just flatten the image and print, but this result will not be much different than applying duotone via the Colorize option in Hue/Saturation. In more advanced scenarios, you will want to separate the duotone layers and use them to control the printed result. You can do this using techniques discussed in the “Printing Duotones” section later in this chapter.


Created: March 27, 2003
Revised: March 1, 2004