Gerber OMEGA CP Reference Manual page 374

360 Chapter 31:
Working with Images
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Stochastic is a dispersed-dot pattern, which minimizes texture and contrast while
maximizing viewing range. The LPI cannot be set using the stochastic pattern.
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Classical Dot is a traditional halftone pattern.
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Spiral Dot is used for special effects. The dot pattern appears to divide the design into
squares and the effect is more pronounced as the number of lines per inch decreases.
Choosing lines per inch
Output resolution is expressed in lines per inch (LPI). The proper setting for a job depends on
several factors:
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final output size
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viewing distance
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original image type (continuous tone image, such as a scanned photograph, or a non-
continuous tone image, such as a product logo or artist's rendering)
A higher LPI setting (smaller dot size) produces a sharper appearance, noticeable transition
between fades (banding), and fewer gray scales. A lower LPI setting (larger dot size) produces a
coarser appearance, especially when viewed close up, but provides a greater range of gray
scales.
The LPI setting is too high if, at the intended viewing distance, the image looks blotchy or
posterized in highlighted areas such as a person's cheek. The LPI setting is too low if, at the
intended viewing distance, the image appears coarse or granular.
Use the following guidelines to estimate the LPI for various sizes and fills. Try adjusting the LPI
setting in increments of 7 to 10 LPI.
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For an Output Size of 5.8 inches (14.7 cm) or less, use a Continuous Tone of 55 - 70 LPI
or a Non-Continuous Tone of 70 - 90 LPI.
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For an Output Size of 5.8 inches (14.7 cm) or greater, use a Continuous Tone of 45 - 60
LPI or a Non-Continuous Tone of 70 - 90 LPI.
To change the lines per inch (LPI)
1 Select the image and click the Image Fill tool to open
the Image Fill dialog box.
2 Choose a halftone type that allows changes in LPI --
Spiral Dot, Classical Dot, or GerberTone STC Photo.
3 Enter a value in the LPI text box.
4 Click OK to return to Composer.