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Files with gradients, meshes, or color blends can be difficult for some printers to print smoothly (without discrete bands of color) or at all.
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.
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Select Graphics on the left side of the Print dialog box, and select Compatible Gradient And Gradient Mesh Printing.
Note:
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.
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 |
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.
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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%.
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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
, and
click the beginning point and the endpoint of the gradient.