Lab-to-Spectral: Create a Characterization From an MX4 Proof Profile
If you have an already existing library of validated MX4 proof profiles created in GMG ProfileEditor, you are now able to use the process colors defined in the profiles as inks in GMG OpenColor. The Lab-to-Spectral function allows you to generate spectral characterization data describing the printing condition out of the MX4 profile.
- Save a great deal of tedious work by simply converting Lab values into spectral data with a few clicks.
- Reuse your valuable library of MX4 proof profiles.
- Manage all your colors in one central GMG OpenColor database.
- With Lab-to-Spectral, you are no longer limited to the combination of four colors described by an MX4 profile. Recombine colors from existing MX4 profiles and from spectral measurement data.
- With the dynamic profile generation in GMG OpenColor, this recombination can even be automated. Just create a job in GMG ColorProof and GMG OpenColor will automatically calculate the correct proof profile.
PhotoProof profiles are not supported. MX4 profiles where one of the channels have been swapped with a different color such as Violet or Green will most likely not give useful results. However, if the swapped color is very similar to the default color, for example, Dark Brown instead of Black, you might achieve satisfying results.
Furthermore, the Lab-to-Spectral feature enables you to generate spectral characterization data from Lab target values for CMYK in the standard exchange format CGATS (txt file format) and ICC. This way, you can use measurement data and ICC profiles created by a third party application.
How to use Lab-to-Spectral for process colors
Create a new characterization or project and define the Printing Process and Media according to the target printing condition of the MX4 proof profile you want to import. Then simply click the Import button on the Tools & Actions pane on the right side. You can then pick the file you want to import in the file browser.
If GMG OpenColor is not able to recognize the proofer gamut, you will need to manually select a gamut file or proofing condition (see "Lab-to-Spectral: No Gamut File Found").
Click the Calculate button to create the spectral data from the profile.
Depending on how well GMG OpenColor was able to find a matching template for the spectral data in the database, the resulting characterization might be used as any other characterization in your database, or only with limitations.
Possible results
| Result | Description |
|---|---|
| Green | Generation of spectral data successful. You can expect the characterization to be close to the true characterization (from spectral measurement values). You can use the characterization like any other and recombine the imported colors with other colors from your database. |
| Orange | Generation of spectral data successful. When calculating a CMYK proof profile from a project using this characterization, you can expect a good quality. If the spectral data was generated from an MX4 proof profile, you can expect that the printed proof is very close to the proof printed with the original MX4 profile. However, a recombination of the colors with other colors is recommended only if the colors are not overprinting. The prediction of the overprint behavior with other colors might be limited. |
| Red | Generation of spectral data failed. This is a rare result and strongly indicates that there is something wrong with the MX4 profile, which should be checked accordingly. Does the CMYK value set within the MX4 profile cover all fulcrums? Or are there empty ones? Has one of the channels been swapped with a different color such as Violet or Green? Is the selected proofer gamut valid? |
If GMG OpenColor is able to create spectral data in sufficient quality, you can click the Save button to proceed with the import.
GMG OpenColor will open the Measurement Data dialog box. Here, you can rename the measurement data. You can click the i button to see a summary of the import settings.
Measurement Data dialog box.
Click OK to finish the import and use the data as a new characterization.
New characterization with CMYK ink characterizations created from an MX4 proof profile. The file name and checksum of the imported MX4 profile can be found in the Comment.
Check the ink sequence. It should match the ink sequence of the target printing condition of the imported MX4 profile.
(MX4 profile only) The profile characteristics Noise, Missing Dots, and Paper Simulation (shown on the More Parameters tabbed page in GMG ProfileEditor) will not be applied when generating the spectral data. If you want to get a printed proof that is very close to the proof printed with the original MX4 profile, you will need to manually edit the calculated proof profile in GMG OpenColor (see "Profile Editing").