Files with gradients, meshes, or color blends can be difficult for some printers to print smoothly (without discrete bands of color) or at all.

Printing gradients, meshes, and color blends

Files with gradients, meshes, or color blends can be difficult for some printers to print smoothly (without discrete bands of color) or at all. Follow these general guidelines to improve the printed results:

  • Use a blend that changes at least 50% between two or more process-color components.

  • Use shorter blends. The optimum length depends on the colors in your blend, but try to keep blends shorter than 7.5 inches.

  • Use lighter colors, or make dark blends short. Banding is most likely to occur between very dark colors and white.

  • Use an appropriate line screen that retains 256 levels of gray.

  • If you create a gradient between two or more spot colors, assign different screen angles to the spot colors when you create color separations. If you’re not sure what the angles should be, consult your print shop.

  • Print to an output device that supports PostScript® Language Level 3 whenever possible.

  • If you have to print to an output device that supports Postscript Language Level 2, or when printing meshes that include transparency, you can choose to rasterize gradients and meshes during printing. As a result, Illustrator converts gradients and meshes from vector objects to JPEG images.

Rasterize gradients and meshes during printing

  1. Choose File > Print.
  2. Select Graphics on the left side of the Print dialog box, and select Compatible Gradient And Gradient Mesh Printing.

    Märkus.

    The Compatible Gradient And Gradient Mesh Printing option can slow printing on printers that don’t have problems with gradients, so only select this option if you experience printing problems.

Setting the proper screen frequency for printing gradients, meshes, and blends

When printing your file, you may find that the resolution of your printer, when combined with the chosen screen frequency, allows fewer than 256 levels of gray. A higher screen frequency decreases the levels of gray available to the printer. For example, if you are printing at a resolution of 2400 dpi, using a line screen higher than 150 results in fewer than 256 levels of gray. The following table lists the maximum line-screen setting you can use with printers to maintain all 256 levels of gray:

Final Imagesetter Resolution

Maximum Line Screen to Use

300

19

400

25

600

38

900

56

1000

63

1270

79

1446

90

1524

95

1693

106

2000

125

2400

150

2540

159

3000

188

3252

203

3600

225

4000

250

Calculate the maximum blend length for gradients

Illustrator calculates the number of steps in a gradient based on the percentage of change between the colors in the gradient. The number of steps, in turn, determines the maximum length of the blend before banding occurs.

  1. Select the Measure tool , and click the beginning point and the endpoint of the gradient.
  2. Note the distance displayed in the Info panel on a piece of paper. This distance represents the length of the gradient or color blend.
  3. Calculate the number of steps in the blend using this formula:

    Number of steps = 256 (number of grays) X Percentage change in color

    To figure out the percentage change in color, subtract the lower color value from the higher color value. For example, a blend between 20% black and 100% black is an 80%—or 0.8—change in color.

    When blending process colors, use the largest change that occurs within any one color. For instance, take a blend from 20% cyan, 30% magenta, 80% yellow, and 60% black to 20% cyan, 90% magenta, 70% yellow, and 40% black. This indicates a 60% change, because the greatest change occurs in magenta—from 30% to 90%.

  4. Using the number of steps calculated in step 3, see if the length of the gradient is larger than the relevant maximum length indicated in the next chart. If it is, reduce the length of the gradient or change the colors.

    Number of Steps Adobe Illustrator Recommends

    Maximum Blend Length

    Points

    Inches

    Cms

    10

    21.6

    .3

    .762

    20

    43.2

    .6

    1.524

    30

    64.8

    .9

    2.286

    40

    86.4

    1.2

    3.048

    50

    108.0

    1.5

    3.810

    60

    129.6

    1.8

    4.572

    70

    151.2

    2.1

    5.334

    80

    172.8

    2.4

    6.096

    90

    194.4

    2.7

    6.858

    100

    216.0

    3.0

    7.620

    110

    237.6

    3.3

    8.382

    120

    259.2

    3.6

    9.144

    130

    280.8

    3.9

    9.906

    140

    302.4

    4.2

    10.668

    150

    324.0

    4.5

    11.430

    160

    345.6

    4.8

    12.192

    170

    367.2

    5.1

    12.954

    180

    388.8

    5.4

    13.716

    190

    410.4

    5.7

    14.478

    200

    432.0

    6.0

    15.240

    210

    453.6

    6.3

    16.002

    220

    475.2

    6.6

    16.764

    230

    496.8

    6.9

    17.526

    240

    518.4

    7.2

    18.288

    250

    540.0

    7.5

    19.050

    256

    553.0

    7.7

    19.507

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