An Overview of Digital Printing Systems - Control of Color Imaging Systems: Analysis and Design - page 6

Halftone and
resolution
enhancement

C C΄

Cyan TRC

ROS

Halftone and
resolution
enhancement

M΄

M

Magenta TRC

Halftone and
resolution
enhancement

Y Y΄

Yellow TRC

Halftone and
resolution
enhancement

K K΄

Black TRC

Latent
image

ESV
sensor

MIMO control
algorithm

Target

Erase Charge

Expose

Clean

Photo receptor

Develop

Transfer

Paper path

FIGURE 1.3 Key processing elements in the DFE and the electrophotographic (EP) process.

part of the rendering process. Trapping parameters are speci c to a device and its

colorant set.
Once the RIP is complete, the input job is transformed from a PDL format to
CMYK separations ready for engine consumption. The separations are usually

generated at the engine resolution (e.g., 600 dpi) for a given paper size (e.g.,
8

pixel. Dependent on the
option selected by the user, DFEs may RIP a given input document to a higher
resolution (e.g., 1200 dpi) than what the printer is designed to handle (e.g., 600 dpi)
and then subsample it to the appropriate printer resolution using standard
techniques. This sequence, of course, results in a slight loss of sharpness but reduces
aliasing effects.

: 5 11 in: ), where each separation is made up of 8 b =

1.4 DIGITAL PRINT ENGINE (ELECTROPHOTOGRAPHIC)
The print engine

— sometimes referred to as the '' marking engine '' — is designed to

convert the electronic separations provided by the DFE into hardcopy color

prints. Figure 1.3 illustrates a typical digital press or printing system based on the
principles of electrophotography (EP) invented by Chester Carlson in 1938 [4].
Unlike offset presses, digital print engine technologies are still evolving to improve

CMYK