G7 ?

[Deleted member 16349]

Hi Erik,
You are correct that CMY density has no direct relationship and would be a poor way to go for determining ideal gray. However, the "triplet" values are not density values, but patch color percentages. Think of it this way. 50C, 40MY is the optimal value to yield the neutral gray (according to G7), but if that patch doesn't actually measure neutral (in CIELab, not density) from your press/printer, perhaps a 50C, 38M, 43Y does. The GrayFinder target has patches of differing CMY percentages to help determine the optimal compensation toward gray.

The GrayFinder method makes more sense than the manual method explained in the webcast. You go right to the patch that gives the best result to use as the data for compensation. I guess it is more applicable to the automated method that Don also referred to.

 

[Lukas Engqvist]

If your gray is not the standard then most chances are your DMAX is off or curves are not the right shape. To opt for different value for gray is a little strange, it means that what prints neutral in one press will have a cast in another. Consistency must be equally important for a job in one press over time as in different presses.

 

[meddington]

If your gray is not the standard then most chances are your DMAX is off or curves are not the right shape. To opt for different value for gray is a little strange, it means that what prints neutral in one press will have a cast in another. Consistency must be equally important for a job in one press over time as in different presses.

This is simply curve correction at the Rip level Lucas, only towards a balanced gray. In many cases, gray balance correction would not be necessary but for the reasons you state. If one were adjusting a press toward ISO TVI curves and noticed that individual curves were necessary (maybe the magenta TVI was a bit high for example) it would be the same result...changing the CMY values at the rip to hit the desired target. The reason for balancing toward a neutral gray is precisely because what prints neutral at one press has a cast in another...so balance that other press...either by adjusting inking, or if that's not possible or, via curves.