Changing bitmaps to duotones

To convert an image to a duotone, you change a bitmap to the grayscale color mode and enhance it using one to four additional colors, giving the image greater tonal depth.

The following four variations of the color mode correspond to the number of additional inks:

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Monotone — a grayscale image colored with a single tone

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Duotone — a grayscale image colored with two tones. In most cases, one is black and the other is colored.

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Tritone — a grayscale image colored with three tones. In most cases, one is black and the other two are colored.

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Quadtone — a grayscale image colored with four tones. In most cases, one is black and the other three are colored.

CorelDRAW bitmode tones examples Changing bitmaps to duotones

The four color mode variations. From left to right: the original image, monotone, duotone, tritone, and quadtone.

Adjusting tone curves

When you change an image to a duotone, a tone curve grid that represents the dynamic tone curves that are used throughout the conversion is displayed. The horizontal plane (x-axis) displays the 256 possible shades of gray in a grayscale image (0 is black; 255 is white). The vertical plane (y-axis) indicates the intensity of a color (from 0 to 100 percent) that is applied to the corresponding grayscale values. For example, a grayscale pixel with a color value of 25 is printed with a 25-percent tint of the color. By adjusting the tone curves, you can control the color and intensity of the tone that is added to an image.

Saving and loading inks

You can save an adjusted duotone tone curve and ink settings and then load them for use with other bitmaps.

Specifying how overprint colors display

When you change an image to a duotone, you can specify the colors to overprint when you print an image. Overprint colors are used to preserve color integrity when inks overlap. When you display the image, each color is applied on the screen in sequence, creating a layered effect.

You can view all instances in which the colors you choose for the duotone conversion overlap. Associated with each instance is the color that is produced by the overlap. You can also choose new overprint colors to see how they overlap.

Duotones will hold their color ink information when saving to Encapsulated PostScript (EPS), Portable Document Format (PDF) and CorelDRAW (CDR) file formats. Other file formats don’t support duotone images.

To change an image to a duotone

Click a bitmap.

Click Bitmaps

Mode

Duotone (8-bit).

Click the Curves tab.

Choose a duotone type from the Type list box.

Double-click an ink color in the Type window.

In the Select color dialog box, choose a color, and click OK.

If you want to adjust the color’s tone curve, click the ink tone curve on the grid to add a node, and drag the node to adjust the percentage of color at that point on the curve.

Repeat steps 5 and 6 for each ink color you want to use.

You can also
Display all the ink tone curves on the grid.	Enable the Show all check box.
Save the ink settings	Click Save. Choose the disk and folder where you want to save the file, and type a filename in the Name box.
Specify how overprint colors display	Click the Overprint tab, and enable the Use overprint check box. Double-click the color you want to edit, and choose a new color.

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You can load preset ink colors by clicking Load, locating the file in which the ink settings are stored, and double-clicking the filename.

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