Dynamic CMYK Conversion

Dynamic CMYK conversion calculates new separations when required, aiming to minimize the number of output channels. In contrast, static conversion uses the predefined separation rule from OpenColor without recalculating separations.

Add Dynamic OpenColor CMYK calculation to your conversion template

1. Drag the DYN symbol onto the Spot Colors arrow.
   
2. Select your input project from the Input Color Space drop-down field. 
3. Select your output project. The Output Color Space drop-down field lists all OpenColor projects that contain a separation rule with the selected OpenColor input project.

4. For dynamic conversions, manually activate or deactivate output channels as required.
   

   Note: In fully automated workflows, output channels can also be specified through a Job Ticket or the API.

5. Select the separation preset that fits the purpose of you printing process best. The default separation settings will change depending on the selected preset. 
   
   • Adjust the Total Area Coverage as needed.
   • GCR Level (CMYK): The amount of Black is defined by the separation rule. By increasing the level of Gray Component Replacement (GCR), you can reduce the amount of CMY in gray areas while increasing the amount of Black. Thus, less ink can be used and the resulting output is less sensitive to changes in the printing variables. If the GCR level is set to 0, the total Black ink will be the sum of the Black ink usage for single colors as defined in the separation rule. This setting affects only CMYK inks, not any additional inks that might be part of the ink configuration.
   • Black Start (CMYK): This specifies the percentage at which Black ink is starting to be used and is defined by the separation rule. You can define a higher black start here, which will affect only CMYK inks, not any additional inks that might be part of the ink configuration.
6. Adjust the gamut mapping if desired
   
   • Gray Adjustment to Target Media: This defines how much the paper tint of the target print medium will affect the printed colors. This setting is important if the target printing condition uses a substrate with a different white point than the document's output intent and mainly affects the gray balance and less saturated colors. Moving the slider to the left will preserve the original colors and thus ignore the new paper tint, moving it to the right will have more impact on colors, especially on highlights and gray balance.
   • Black Point Compensation: This can be increased to minimize clipping in shadow areas, preserving image details and allowing full use of the output color space's dynamic range in the shadows. In most cases, increasing the BPC will also lead to a general decrease in saturation. If the black point of the target color space is darker than the black point of the source, BPC might increase the saturation. If you need a color as deep black as possible or want to avoid color shifts, you can decrease or deactivate black point compensation by moving the slider to the left. We recommend to use a high BPC value for CMYK-to-CMYK separations of image data and to use a low BPC value for packaging printed on coated media.
   • Gamut Expansion: This allows you to exploit the full available color space of your printer and is useful for all printers with a large color space, with CMYK only or with additional inks. Using gamut expansion will boost colors to the edge of the available printer color space and might change them drastically, while the gray balance remains unchanged. Please note that color boosting is only possible if the target color space is significantly larger than the source. If your printer uses additional inks, also select the option Allow Additional Inks in Overprints from the purify settings for a maximum effect
7. Adjust the purify settings if desired
   
   • Keep Black Pure: This keeps the black axis pure, so Black will not be supplemented with or replaced by CMY.
   • Keep 100% Black at 100% : This keeps Black at 100%.
   • Keep CMY Pure: This keeps Cyan, Magenta, and Yellow pure, so they will not be supplemented or replaced by other colors.
   • Allow Additional Inks in Overprints: This defines how strictly the ink splitting definition from the separation rule will be applied to overprinting colors. If enabled, the overprint settings from the separation rule will still be regarded, but GMG OpenColor might also use additional inks if it makes sense to do so. Allowing additional inks in overprints is especially useful in cases where the resulting color will be substantially different from the individual colors, for example, when blue is overprinted with yellow.
      

Separation rule variants

When ColorServer processes a job using a conversion template with dynamic color conversion, it may generate new profiles for the applicable separation rule if the requested color combination has not been calculated previously.

The newly generated profiles are listed in OpenColor in the profile list for the corresponding separation rule.

The details of the separation rule show the variants that have been triggered by ColorServer:

The separation rule details show the variants triggered by ColorServer. To display the Lab values for all tints, click the eye icon (Show Tints).

See as well:

• Conversion templates
• Dynamic Profiling
• Dynamic Spot Color Conversion
• Dynamic RGB Conversion