Moire pattern on offset anicolor press

[jotterpinky]

A quick update on this situation. We went ahead and had some plates imaged by Heidelberg to rule out either our angle set or the anilox roller. The plates printed perfectly with no apparent moire pattern. These were obviously imaged with a Heidelberg RIP and plate setter. I checked our screen angles against those run by Heidelberg and they matched exactly. The only thing I'm unsure of would be the exact dot shape used. We normally run an elliptical dot and I have tried a round dot as well but to no avail. overall Heidelberg has been rather good at addressing the issue and we are now investigating other possibilities. Do you think this could possibly be a hardware (I.e. Plate setter) issue or is it almost certainly a rip issue? Any thoughts.

By the way the fabric moire I posted earlier could almost certainly be caused by the fabric itself but what about the brown sample I posted earlier. This was a solid brown rectangle generated by Adobe illustrator as a vector graphic. I can't imagine it would be subject to "subject moire".

I'm concurrently looking at a new screening methodology as well that hopefully would also solve this problem as well. I've been investigating this for several months to gain more of a competitive differentiator and it seems it might also solve this issue although I'm sure it has it's own host of problems associated with it. I'm most intrigued with digitally modulated screens and was wondering if anyone has had experience with it. The screening I'm referring to is auraia screening. Any thoughts on it in comparison to other FM / XM incarnations.

 

[rbailleu]

if the Heidelberg plates were the same image and had no moire, Id say you have a screening issue in your rip. If I could afford an anicolor sm52, I might consider just looking into a Heidelberg rip or ctp system. it would appear that they have a superior screening algorithm. or for that matter there are other companies that have great rips and ctp. xitrons hps should take care of this, but we had isssues with xitron on our di too. best suggestion is a different rip

 

[gordo]

We went ahead and had some plates imaged by Heidelberg to rule out either our angle set or the anilox roller. The plates printed perfectly with no apparent moire pattern. These were obviously imaged with a Heidelberg RIP and plate setter. I checked our screen angles against those run by Heidelberg and they matched exactly.

That appears to rule out your screen angles as an issue.

The only thing I'm unsure of would be the exact dot shape used.We normally run an elliptical dot and I have tried a round dot as well but to no avail.

Dot shape only affects single channel moiré - which doesn't seem to be your problem. Round dot is the best dot shape for offset CtP (for reasons explained many times in this forum).

overall Heidelberg has been rather good at addressing the issue and we are now investigating other possibilities. Do you think this could possibly be a hardware (I.e. Plate setter) issue or is it almost certainly a rip issue? Any thoughts.

It's unlikely to be a RIP problem. It's possible it's a Platesetter problem, e.g. the RIP runs at one resolution but the platesetter runs at a different one.

By the way the fabric moire I posted earlier could almost certainly be caused by the fabric itself but what about the brown sample I posted earlier. This was a solid brown rectangle generated by Adobe illustrator as a vector graphic. I can't imagine it would be subject to "subject moire".

Heidelberg should be able to analyze that press sheet and figure it out. Moiré is very specific in the causes that make it appear.

I'm concurrently looking at a new screening methodology as well that hopefully would also solve this problem as well. I've been investigating this for several months to gain more of a competitive differentiator and it seems it might also solve this issue although I'm sure it has it's own host of problems associated with it. I'm most intrigued with digitally modulated screens and was wondering if anyone has had experience with it. The screening I'm referring to is auraia screening. Any thoughts on it in comparison to other FM / XM incarnations.

I highly recommend that you look at Auraia II DM screening. I'm currently involved in implementing it at a newspaper publisher and its performance is very impressive.
You can get a very good demonstration brochure with many real-world samples from Hamillroad.

best, gordo

 

[Green Printer]

I have ran Auraia II DM. I think it is the best screening available. Andy Cave has done a tremendous job. Andy wrote the harlequin rip code, First Proof and Auraia screening. The Auraia screening algorithm is over ten years old but could not be cost effectively implemented because of the high horsepower computers needed to calculate the algorithm. With the I7, xeon and other multicore processors, multithreading and cheap gigabit ram Auraia is a reality.