The output result when printing the same file on different machines does not look identical. To achieve identical results the input data has to be converted using a color management system.
The color conversion is typically done using ICC-Profiles which are used to perform a conversion from input device data (such as RGB) to output device data (such as CMYK) using a translation color space. This translation space is usually CIELAB and known as PCS (Profile Connection Space).
In todays print workflows digital input files such as PDF files are converted in systems called a RIP, DFE (Digital Front End), Controller or similar. To achieve good conversion speeds the accuracy is often limited to 8Bit. This limitation is not a problem in practice if the machine is brought into a "linear" state. Thanks to this linearization the necessary corrections to achieve accurate color output is minimized and the available 256 steps per channel (8 Bit) are enough.
Method 1.
G7 Curves applied in Controller
MYIROtools generates one correction curve per output channel. These curves are used to make sure that the output of the press before any color conversion is applied meets the requirements of the G7-methodology.
The curves can be loaded into the controller of many types of printing machines.
Method 2.
G7 Curves applied as DeviceLink
MYIROtools generates one correction curve per output channel and saves these curves as CMYK2CMYK DeviceLink Profile. This DeviceLink-Profile can be used if the Controller is not capable of applying linearization curves.
Step 1
Start the G7 Press Setup Workflow and select "Create G7 linearization".
Then click "Next".
Step 2
In the next step you need to measure the P2P51 chart.
You can open it through the workflow and print it or use a chart that you've already printed.
Make sure to have all color conversions switched off and only the standard curves (usually linear) applied.
Step 3
After the measurement is completed select the appropriate measurement condition (usually M1) and click "Next"
Step 4
Choose a name and a storage location for your G7-correction.
MYIROtools will save a correction DeviceLink ICC-Profile and a .csv-file containing the correction values.
Step 5
Enter the values from the .csv-file in the linearization dialogue of your DFE.
Please refer to the user manual of the DFE to select the correct interface.
Step 6
The G7-Linearization is now finished.
You can continue creating a press profile.
For a digital printing machine it is necessary to create a profile.
For an offset press you are finished and can accept data that was prepared using a CRPC for the paper you are using for production.
Step 1
Start the G7 Press Setup Workflow and select "Create G7 linearization".
Then click "Next".
Step 2
In the next step you need to measure the P2P51 chart.
You can open it through the workflow and print it or use a chart that you've already printed.
Make sure to have all color conversions switched off and only the standard curves (usually linear) applied.
Step 3
After the measurement is completed select the appropriate measurement condition (usually M1) and click "Next"
Step 4
Choose a name and a storage location for your G7-correction.
MYIROtools will save a correction DeviceLink ICC-Profile and a .csv-file containing the correction values.
Step 5
To use the G7 DeviceLink it is necessary to "bake" it into the complete color conversion.
Therefore the next step is the creation of a color space conversion (CSC) DeviceLink Profile.
Step 6
In the process you can choose from four different presets.
1) Digital Production Printing
Suitable for any production printing process where a CMYK reference should be achieved
2) LFP Production
Obtains more vivid results
3) Simulation
Mainly for proofing purposes
4) RGB Production
Use if the source data is RGB
Step 7
When asked choose an appropriate name for your color space conversion profile.
Step 8
Now the G7 Correction needs to be linked with the color space conversion.
This is called "concatenation"
Step 9
Select the color space conversion DeviceLink created in the previous step as first (source) profile.
Then select the G7 correction profile as second (destination) profile.
Choose a meaningful name and save the profile.
Step 10
The profile we've just created contains the full conversion from source to destination to linearization.
This could be e.g.:
CRPC6.icc - MyMachines_Output_Profile.icc - G7Correction_for_my_machine.icc
For other source profiles you need to create another concatenation.
