Gerber OMEGA CP, Справочное руководство

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214 Chapter 18:
Choosing and Assigning Halftones
Choosing the halftone type
Halftone types exist to provide specific effects when thermal printing. OMEGA offers two
standard types (classical dot and spiral dot) and four types specially developed for thermal
printing in the sign industry (the Gerber Tone
™
series).
Classical dot is a traditional halftoning pattern. When you choose this halftone, you must also
choose the LPI.
Spiral dot is used for special effects. The dot pattern appears to divide the design into squares
and the effect is more pronounced as you decrease the LPI (make larger dots).
GerberTone (the system default) is the most versatile, providing optimum print quality for
most jobs. It is similar to classical dot and provides superior results when blending fades
because it reduces banding. This advantage is more pronounced in larger jobs (which are
usually viewed from a distance) because the dots may be too large for a small job. The LPI is
built into this halftone and cannot be changed.
GerberTone Long is used in long shapes and signs such as those on vehicles and trailers. It
reduces banding. The LPI is built into this halftone and cannot be changed.
GerberTone Fine is used for filling smaller shapes such as name and address labels. The LPI is
built into this halftone and cannot be changed.
GerberTone STC Photo is designed for use with bitmaps or other images when printing to the
GERBER EDGE, EDGE 2, EDGE FX, and MAXX 2. It provides a wide range of colors and
intensities at variable lines per inch (LPI) settings. When using GerberTone STC Photo with the
MAXX 2, the LPI range is 4 to 35 LPI.
Choosing the LPI
Larger dots (a lower LPI) produce a coarser appearance, especially when viewed close up. The
advantage of larger dots is that they provide a greater range of tints (often called
gray scale );
therefore the transition from tint to tint has a gradual appearance.
Smaller dots (a higher LPI) produce a sharper appearance, especially when viewed up close.
However, they provide a smaller range of tints and the transition from tint to tint is noticeable
(often called
posterization ).
The proper LPI for a job depends on:
♦
the thermal printer used to print the job (EDGE, EDGE 2, EDGE FX or MAXX 2)
♦
the final output size
♦
the viewing distance
♦
the original image type (a continuous tone image such as a scanned photograph or a
CD-ROM photograph; a non-continuous tone image such as scanned line art)
♦
the fill type (solid or linear/radial)