Adobe 13102498 - Photoshop CS3 - Mac User Manual page 506

Convert an image to duotone
Convert the image to grayscale by choosing Image > Mode > Grayscale. Only 8-bit grayscale images can be
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converted to duotones.
2 Choose Image > Mode > Duotone.
In the Duotone Options dialog box, select Preview to preview the image.
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For the Type option, select Monotone, Duotone, Tritone, or Quadtone.
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Click the color box (the solid square) to open the color picker, then click the Color Libraries button and select an
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ink book and color from the dialog box.
Note: To produce fully saturated colors, specify inks in descending order—darkest at the top, lightest at the bottom.
6 Click the curve box next to the color ink box and adjust the duotone curve for each ink color.
Set overprint colors, if necessary.
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Click OK.
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To apply a duotone effect to only part of an image, convert the duotone image to Multichannel mode—this converts
the duotone curves to spot channels. You can then erase part of the spot channel for areas that you want printed as
standard grayscale.
See also
"About spot colors" on page 501
Modify the duotone curve for a given ink
In a duotone image, each ink has a separate curve that specifies how the color is distributed across the shadows and
highlights. This curve maps each grayscale value in the original image to a specific ink percentage.
To preview any adjustments, select the Preview option in the Duotones Options dialog box.
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Click the curve box next to the ink color box.
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The default duotone curve, a straight diagonal line, indicates that the grayscale values in the original image map to
an equal percentage of ink. At this setting, a 50% midtone pixel is rendered with a 50% tint of the ink, a 100% shadow
is rendered in 100% color, and so on.
Adjust the duotone curve for each ink by dragging a point on the graph or by entering values for the different ink
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percentages.
• In the curve graph, the horizontal axis moves from highlights (at the left) to shadows (at the right). Ink density
increases as you move up the vertical axis. You can specify up to 13 points on the curve. When you specify two
values along the curve, Photoshop calculates intermediate values. As you adjust the curve, values are automatically
entered in the percentage text boxes.
• The value you enter in the text box indicates the percentage of the ink color used to represent the grayscale value
in the original image. For example, if you enter 70 in the 100% text box, a 70% tint of that ink color is used to print
the 100% shadows.
Click Save in the Duotone Curve dialog box to save curves created with this dialog box.
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Click Load to load these curves or curves created in the Curves dialog box, including curves created using the
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Arbitrary Map option.
PHOTOSHOP CS3 499
User Guide