The Tab Black Generation: Black Point and TAC

The Total Area Coverage (TAC) and the TAC for the black point (Black-TAC) can be defined under Black Point and TAC. The Black-TAC represents the darkest color value of the profile which is usually identical with the maximum TAC.

Many modern printing systems allow a black point that is generated by using a low amount of ink. Sometimes the darkest color can be printed using pure black which means that in extreme cases a black point with 100% K may be sufficient. Obviously, such a low TAC does not work for other color areas – it would not even be possible to print a true red! Therefore we separated the Black-TAC from the general TAC in both printer and DeviceLink profiling. This allows to use the best setting for Black Calculation without restricting the color space.

The value for the black point (Black-TAC), which results from your settings, will be displayed after a short calculation time below the text box Custom (outlined in red in the screenshot below).

The Lab value is particularly handy for assessing the effect on the black point when changing the TAC or Black-TAC. The smaller the L* value, the deeper the black and the higher the contrast.

TAC and Black-TAC can be adjusted separately in CoPrA

The total area coverage (TAC) – defined by the separation – and the Black-TAC are identical in traditional printing systems. However, industrial printing applications and many digital printing systems show that the black point can be selected much lower than the total area coverage. To achieve a sound gray balance with a high contrast while maintaining highly saturated colors it is necessary to separate these two settings.

The Settings for Black Calculation are explained here.

Advantages of a separate Black-TAC

We would like to demonstrate how important it is to adjust the Black-TAC independently from the total area coverage (TAC) using a digital printing system. Let’s assume the Black-TAC and TAC could not be set separately and we had to use identical values for both of them. If you selected the option Auto to calculate the black point and set a TAC of 400% (and therefore a Black-TAC of 400% as well), CoPrA would calculate the best black point for this case. The result would be a total area coverage of 275% with a neutral black point (a* and b* are 0 respectively), but with a very light L* of 16.6 (outlined in red in the screenshot below).

However, CoPrA allows to set the Black-TAC separately from the total area coverage (TAC). As pure black is usually used as darkest printing color in digital printing systems, the Black-TAC can be reduced to 100% which results in a black point with a significantly lower L* value of 11.9. Using a separate setting for the Black-TAC achieves a significantly higher and better contrast than a TAC which is linked to a Black-TAC of 300%. Additionally, a total area coverage (TAC) of 300% ensures highly saturated colors. These precise settings are only possible with separate TAC values.

This entry was posted in Black Generation settings, Black Generation settings for DeviceLinks, CoPrA4, DeviceLink Profiling, Printer Profiling, What's new in CoPrA 3.3?. Bookmark the permalink. Trackbacks are closed, but you can post a comment.

Post a comment and download files

You must be logged in to post a comment and/or to download files.