Colour Adjustments - Canon imagePRESS C800 Series Technical & Service Manual

Colour adjustments

In the [System] tab there is a dedicated section called [Colour adjustments] in which colour
aspects can be adjusted. In this section you can perform the Colour calibrations and edit the
CMYK curves.
Calibrations
Due to external environmental circumstances, like temperature and humidity, consumables and
print quality change over time. These changes effect the colour quality of the printed documents.
Although the printer performs automatic adjustments on a regular basis, you are advised to
calibrate the printer configuration regularly. The calibration procedure consists of 3 steps. Always
perform these steps in the given order.
• Shading correction
The Shading correction procedure corrects slight density unevenness from front to back across
an image drum. After measuring a test print the power of the laser beam is automatically
adjusted across a laser scan line. The Shading correction assures consistent colour planes over
the whole print.
• Auto gradation adjustment
The Auto gradation adjustment procedure is a precise calibration of the gradation, density and
colour settings of the printer. A test print is used to scan and to correct the irregularities
automatically. In this part you can choose between:
1. Full adjustment
This option does the auto gradation adjustment by printing sheets and measuring them,
either automatically or via the glass platen.
2. Quick adjustment
The measurement is done without printing any paper but is considered to be less accurate
than the Full adjustment. We advise not to use this adjustment.
This calibration can be done for all paper types (normal, heavy, extra heavy) in one step or
for each paper type individually. This can be selected in the Settings Editor.
• Media family calibration
The Media family is a group of media that uses the same output profile. The controller
provides by default the media families coated and uncoated. An expert can create a new media
family for a specific group of media. A media family refers to 1 colour profile per halftone:
'Normal', 'Fine' and 'Error diffusion'. The controller has to be calibrated for each media family
and halftone.
The shading correction and media family calibration are executed by using an I1 photo
spectrometer. The PRISMAsync for imagePRESS C800 Series supports both UV- and non-UV
meters.
The customer can set some parameters regarding the engine calibration. These settings are:
Colour adjustments
Chapter 4 - Using the PRISMAsync 47