Calibration Files
The optimized printer setting regarding the amount of ink applied to the paper is called calibration. This optimization aims at obtaining a maximum ink density at the lowest possible ink consumption. The calibration result is saved as a separate calibration file (.epl file).
Each calibration file is assigned to a paper profile file and automatically loaded to Color Proof Pro together with the assigned paper profile.
Color Proof Pro differentiates between two calibration types:
Creation of paper profiles and calibration files.
Correction of an existing calibration file.
In Color Proof Pro, "paper profiles" refer to files that describe the properties of the different papers concerning color reproduction. The term "paper profile" should not be mistaken for the term "color profile". Color profiles (ICC profiles) result from connecting calibration data and paper profiles after editing with a tool like Prinect Color Toolbox.
Basic Procedure for Creating a Color Profile
During calibration, a calibration file (.epl file) is generated. When calibration is finished, an ICC test chart can be printed for measurement.
A calibration file contains details on the proportional amounts of each of the inks that are used when creating the paper profile. The calibration file also contains a reference to its paper profile file. The "Connect Profiles" module is responsible for this (see Connect Profiles). Calibration determines the physical properties of the interaction between ink and paper and optimizes these properties during profile generation.
The calibration file of a specific color profile automatically loads as well when this color profile is set later in Color Proof Pro or a Prinect application that uses Color Proof Pro as the driver. In this way, the properties of the underlying calibration are set for output, affecting each of the print processes run with this profile.
You can find details about how to run calibration under Create Calibration or for printers with a built-in colorimeter under Create Automatic Mode and ICC Profiles in Color Proof Pro.
The color reproduction of a printer can vary over time. With a recalibration, you can readjust the color reproduction of a printer to the state it had when the paper profiles were generated, i.e. during base calibration.
In this way, it is not necessary to generate all paper profiles again if the printer has changed its color application properties over time.
Recalibration can run using a measuring device (spectrophotometer) or by visual assessment. While a measuring device provides exact data, visual recalibration is based solely on assessments of an observer and matching manual changes.
You can find details about how to run recalibration under Re-Calibration by Measurement.
When and why is a base calibration or recalibration necessary?
You must run calibration in the following cases:
•Calibration
Calibration is always required if you generate custom paper profiles and you want to use these instead of the generic paper profiles that are are shipped with the software. To ensure an exact color reproduction, we recommend generating custom paper profiles for all paper types used.
Recalibration must run in the following cases:
·Running recalibration at regular intervals ensures that the color reproduction of a printer remains constant. You should run recalibration every two weeks if a printer is used very frequently.
·You must also run recalibration if only paper profiles are available that were not specifically created for the printer that is to be used. If, for example, existing paper profiles were generated with another printer of the same model, you should run recalibration to match the profiles to the printer in use.
Even printers of the same mass production model feature slightly different color application properties that may result in different color reproduction. Recalibration can correct such differences.
Recalibration makes sure that the color reproduction of the printer in question matches that of the reference printer that was used for calibration and for creating the paper profile.
·After a printhead exchange, you should run recalibration.
·An exchange of printer components can change the color properties of the printer.
·You should run recalibration if you notice that the proof prints no longer match older proofs exactly.
Note: Make sure to operate the printer at constant ambient conditions (humidity, temperature, no direct sunlight, etc.). You then will generally get stable print results with a calibrated device.