The Color Correction tool allows you adjust your measured or otherwise defined color values to get closer to the actual target colors of the print product. You can adjust the paper tint and other media related properties to better match the production material.
The target color of an ink defines how the ink is expected to print—and how it will be measured—on the actual production material. It serves as the reference point for proofing and color verification during print production.
Both the solid ink target value and the tone value curve can be corrected within a characterization. By default, these characterization properties apply to all projects that use this characterization. However, they can be overridden at the project level. Project-level changes affect only the current project and all profiles and separation rules derived from it.
How to correct the solid ink target value
- From a Characterization or Project, on the Tools & Actions panel, click Color Corrections.
- From the ink list on the left, select one or more inks.
Hold CTRL to select multiple inks. - Change the Target Mode OR select Custom to directly edit the target value.
The target values of the selected inks are updated immediately, and the preview reflects the changes in real time.
Example: In the screenshot, a single ink "PANTONE 240 C" is selected.
The tone value curve of the selected ink is displayed in the graph (1), illustrating its tone value behavior.
You can change the Target Mode and directly enter a custom target value (2) for the solid ink. As soon as the target value is modified, the solid ink preview (3) and the tone value behavior (4) are updated accordingly.
For each color tone, the preview displays:
the color values from the characterization (top left), and
the color values that will be used in the profile (bottom right).
Additional inks can be selected to display the overprint behavior (5). This allows you to immediately see how the color corrections impact overprinting inks.
Tone value curve
The graph displays three tone value curves, which are explained in the table below.
The Calculation Method used to generate these curves is shown beneath the graph. You can change the calculation method as long as the curve has not been manually edited and no gradation curve has been loaded. When the method is changed, the graph is updated automatically.
| Line | Shown data |
|---|---|
| Dashed line in ink color | Original tone value behavior derived from the characterization. |
| Solid line in ink color |
The tone value behavior actually used for profiling. This curve is calculated by the application based on the original curve and the target curve. If you are working in Murray–Davies (MD) mode, you can use the eye button to show or hide the SCTV curve, and vice versa. |
| Dashed gray line, black data points |
Loaded target gradation curve. From the drop-down list, select Load Curve to load a gradation curve from the database. To modify the curve, select Edit Curve and click on the line to add or move data points. Because this curve is often partially overlaid by the actually used tone value curve, the dashed gray line may be difficult to distinguish in the graph. |
How to correct the tone value curve
Once a tone value curve has been manually edited or a gradation curve has been loaded, the Calculation Method can no longer be changed. To switch to a different calculation method, you must first reset the curve.
GMG OpenColor still allows you to view a Murray–Davies curve in SCTV mode, and vice versa, so you can compare how the curve would appear under a different method.
- From a Characterization or Project, on the Tools & Actions panel, click Color Corrections.
- From the ink list on the left, select one or more inks.
- From the drop-down list, select Load Curve.
The Select Gradation from Database dialog box opens and displays only gradations of the Tonecurve type. - Select a gradation from the list and confirm with OK.
—OR— - Click Import to import a gradation curve from a text file.
The graph and preview are updated automatically to reflect the changes.
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