Using Device Link Profiles to improve color consistency

[Erik Nikkanen]

Yes, but unfortunately I no longer have the data. If you have access to a spectrophotometer you could measure the Lab values of the sample I gave you. Send them to me and I'll plot them.

It looks like this:



The blue dots are 133 lpi and 200 lpi AM. The other dots are 10 and 20 micron FM and 20 micron first order FM.

This raises an interesting question. Since halftone screens affect hue - what is the correct color of a 50% tone? And therefore which halftone screen best maintains the fidelity of that color.

best, gordo

Gordon,

Sorry I don't have a spectrophotometer. It would be nice to know just for curiosity.

The plots are great. What I am a little surprised about is how soon the colour of the AM and FM screens deviate from each other at the top of the screen % range. I was expecting the values to converge a bit earlier.

For science reasons, it is interesting to look at the colour changes and values at the 50% or other points. Now there seems to be a resurgence in the interest in micro measurements of colour in dot structures. Some recent technical papers seem to be covering this topic. It is not new. I have seen many years ago some work on the same issue.

I say that it is interesting for science reasons but for practical reasons, I have come to view the whole dot gain, issue as being only related to process control on press. I view the whole problem of colour reproduction as being one where dot issues are mostly irrelevant. As long as some kind of structure can be printed consistently, one can make a predictable procedure to reproduce colour given that is within the gamut of the set of materials and device. Of course there are other issues but I see the potential for a very simple approach to colour reproduction that does not require much colour science or intervention. It does not require curve adjusting at all. It would be very automated, quick and simple to use.

Of course, I am looking at the future again and not at the present. That seems to be what always gets me in trouble. :-)

[gordo]

I say that it is interesting for science reasons but for practical reasons, I have come to view the whole dot gain, issue as being only related to process control on press.

Although it is touted as such, I don't think that dot gain has much value as a process control on press (at least as measured in the color bar). However, it can be useful forensically to understand what may have caused the presswork to fail to hit the target.

Dot gain, actually dot area which is the result of dot gain, is more useful in defining the print characteristic as well as helping to determine if the inks/press ink units are performing properly.

best, gordo

[Erik Nikkanen]

Although it is touted as such, I don't think that dot gain has much value as a process control on press (at least as measured in the color bar). However, it can be useful forensically to understand what may have caused the presswork to fail to hit the target.

Dot gain, actually dot area which is the result of dot gain, is more useful in defining the print characteristic as well as helping to determine if the inks/press ink units are performing properly.

best, gordo

Yes, of course. In my mind I was mixing solid density with the dot stuff. SID is for process control. Dot size for trouble shooting as you implied. Duh.

[dpierce@packgraph.com]

just for the sake of clarity. . .
Shortly before GraphExpo, Don Hutcheson gave a presentation at my company and stressed that G7 is a method - that the ISO gets quite upset when someone else suggests that they are issuing specs.
-Dan