01 Network control
Digital printing adopts digital hybrid
screening technology, which uses the characteristics of AM screening, FM
screening and digital control hybrid screening technology for reference. It not
only embodies the advantages of FM screening, but also has the stability and
operability of AM screening. Compared with the traditional screening
technology, the screening technology has a great improvement in both the output
speed and the resolution. The perfect combination of CTP technology and CTP
technology can make the prepress or book
printing present perfect dot effect.
02 Color control
Color is an important measure of image
reproduction effect. Color control in traditional printing is based on density
control. The specific methods include gray balance, color correction, optimal
printing density control, dot control and transfer. The digital printing
process is an open system. The input, processing and output devices may come
from different manufacturers. The color description and expression of different
devices are also different. With the increase of the use times of the same
equipment, the difficulty of color reproduction is also increased. The color
information of color image should not only be presented on different display
devices, but also transmitted between different media. In this regard, ICC, the
international color organization, has developed ICC Profile to describe the
color features of devices, through which cross platform color communication can
be realized.
03 Data output and management
With the advancement of the digital book printing process, the amount of
data is increasing, which requires the optimization of the data transmission
and management process on the network. Therefore, in the field of prepress, OPI
(open press interface) specification and DCS (desktop color separation)
specification are formulated. The OPI specification contains a series of
postscript compliant comment statements, which allow low resolution images to
replace high-resolution images in typesetting, and then automatically replace
them with high-resolution images by OPI server when color separation output, so
as to reduce the amount of data in network transmission. DCS specification
includes a main EPS file and multiple high-resolution color separation files.
The EPS file format is extended to manage the whole color separation process of
desktop publishing system, which can shorten the production time, reduce the
requirements for equipment, and ensure that the data files will not be missing
in the transmission.
04 Printing control register
In digital printing, CCD camera is often
used to monitor the registration of printing machine, and automatic
registration control is carried out through the printing machine in book printing process. The advantages
of using CCD camera for registration are that it adopts image processing
technology and has high registration accuracy; it allows printing other content
around the printing detection color code; it can automatically distinguish the
color code and non-color code content; it improves the utilization rate of substrate;
it can adapt to small color code; and the registration speed is fast.
Digital printing is the development trend
of printing technology. To realize its digitalization and standardization
control is our goal. We expect more quality detection and control methods in
the future to achieve high quality digital printing in book printing process.
