Automatic Spectral Correction
GMG OpenColor offers an automatic spectral correction for measurement data. GMG OpenColor averages duplicates, removes outliers, and smooths the measurement data.
You will get the highest possible profile quality, both for proof and separation profiles, even if the data quality is limited, for example, due to printer instabilities and noise or due to media characteristics. This feature eliminates the need for an external tool, saving investment costs and time. It also avoids a smoothing based on Lab values, thus providing an ideal basis for the GMG OpenColor Prediction Engine. Proof profiles will achieve a better print-to-proof match, so you might need less or even no optimization cycles when creating the profile.
This feature is available only for characterizations.
How to apply the automatic spectral correction
To use the automatic correction, the characterization settings, i. e. printing process and media, need to be fully defined. The selected test chart needs to match the measurement data, i. e. the patches found in the measurement data need to be available in the test chart. The Measurement Data dialog box, see screenshot, shows the Match number (2). The Match needs to be at least 95% to enable the use of the automatic correction.
- Import measurement data
—OR—
click the Measurement Data button (1) in the Tools & Actions pane if you want to use the correction on already existing measurement data.
GMG OpenColor will open the Measurement Data dialog box. If you imported multiple matching data sets, GMG OpenColor will automatically average the data and show the name "Combined Measurement File". GMG OpenColor shows the inks found in the measurement data. If the used test chart has not already been defined, GMG OpenColor automatically analyzes the data and tries to recognize it. - Specify the measurement condition.
- Enter a percentage value limit (3). This preserves printing process related non-linear behavior in the measurement data that you want to simulate in the proof and not get smoothed away.
Measurement values below the selected percentage will be preserved. - Start the correction by clicking the arrow button (4).
Measurement Data dialog box before the correction.
The dialog box lists all measurement data sets in a table and shows the corresponding inks.
Measurement Data dialog box after the correction.
After the correction, the Measurement Data dialog box shows the deviation from the original measurement data (1). This gives you an indication of the data quality and how much impact the correction has on the data.
- For further analysis, you can show the results of the correction (2) in form of a table or in the test chart layout. The table view shows Lab values for all measurement values before and after the correction, and the difference between them. You can sort the table by the columns. You can export the table as CSV. Please note that the displayed Lab values are provided only to give you a simplified view of the corrections. The actual corrections are applied directly to the spectral data.
- You can revert the measurement data to the original state by clicking the undo button (3).
- Clicking the Export button (4) allows you to recover the original measurement data files if you have no longer access to them. All files will be exported exactly as they have been imported to the selected target folder. It is also possible to export data that was measured directly in GMG OpenColor. (It is not possible to export factory-default application data.)