A 3/C grey patch is completely useless for process control in an ink optimized workflow. What I'm experimenting with is the notion of using it as a SID reference instead of solid color patches. This is for application in a newspaper printing. I'm also trying to use it as a training tool for the press operators so that they can get a feel for how their SID moves affect (or more accurately don't affect) different types of imagery.
Adding the patch after the optimizing process adds complication and time to the workflow. I'm wanting to avoid that.
An optimized CMYK grey patch would have less than no value for the reasons you and I gave.
best, gordo
OK, I understand that if there is ink optimization by taking out some of the grey cmy, the printed image will not be so affected by changes in solid density. That would mean that the accuracy of the final separations are very important in obtaining the desired colour of the printed image since there is not so much the operator can do in that situation.
But I hope you are not suggesting that any SID values are OK. I would think that at least the SID values need to be in a specific range. Especially where one has no grey in the print but only combinations of one or two screens of the cmy channels. With only one or two channels I would think that density control again becomes important or at least more important than in an area that has the ink optimization applied to remove some of the CMY inks by reducing the dots sizes.
Also I would add that one of the purposes for aiming at SID values, even if those inks are not used in line with those patches is due to the benefit of having a reasonably consistent ink film across the form rollers. An uneven ink film can cause ink to move laterally from an area that does not use all the ink to an region that does use the ink and can affect its control.
Even within an image one can have small areas where cmy grey exists and where it does not exist. This can be next to each other or in line with each other. Removing cmy grey will only affect the parts of the image. Density control is still required to maintain the non cmy grey parts of the image.
Another dynamic issue is caused by the reduction of ink needed in line with a control patch. This dynamic exists for not only grey removal but also for going to FM screening from AM screening. The reduction of the ink required will move the dynamics of the ink feed to a condition that looks like a lower coverage condition and lower coverage is more difficult to control density. With FM, the additional situation where screens are not affected by changes in ink film on the form rollers means that the more solid or high screen values areas are more affected by variations in ink feed. These are probably not so significant but they are something to think about.
Also specifically with newspaper inks, which are weaker than commercial or packaging printing inks, similar moves with ink keys would not result in the same amount of density change. It would look less sensitive.
As you know, my view is that ultimately control of density is what is critical and should be solved. When that happens, the other issues would be much less critical and easier to deal with. Just my view.
