elliptical p

[Slammer]

Just got into a bit of a argument with little big boss who claims that elliptical p is the newspaper dotshape of choice, whereas I would favor Round.
I have had a look around and can not find anything to support his claim.
has anybody heard about this?

 

[prepressing]

Have you tried using Euclidean? It is actually the default dot shape for most Harlequin RIPs and works well for a variety of printing methods including newsprint.

Elliptical P is typically what our customers with DI presses use. I don't know how well it would work for newsprint. You can view a screenshot of the Harlequin dot shapes on the following page - perhaps this will help you:
Harlequin Precision Screening in the RTI Harlequin RIP Separation Software

 

[gordo]

Just got into a bit of a argument with little big boss who claims that elliptical p is the newspaper dotshape of choice, whereas I would favor Round.
I have had a look around and can not find anything to support his claim.
has anybody heard about this?

EllipticalP is virtually the same as elliptical dots from other RIPs
Euclidean is the same as the default AM screen from other RIPs

For CtP (not just newsprint) if you're going to use an AM/XM screen then, in order of preference, the choice would be:
1) Round dot (round through the tone scale)
2) Elliptical (Elliptical P) (elliptical to diamond to elliptical through the tone scale)
3) Euclidean (round to square to round the tone scale)

The reasons are explained here: Quality In Print: AM Screening Dot Shapes

best, gordon p

 

[lyzan]

Just got into a bit of a argument with little big boss who claims that elliptical p is the newspaper dotshape of choice, whereas I would favor Round.
I have had a look around and can not find anything to support his claim.
has anybody heard about this?

Elliptical p is the suggested dotshape from industry for Harlequin user. The reason behind it is the dot link up. Basically for newspaper, it is much better if you will you use elliptical dot shape. Try to investigate the difference between the dot link up of round and elliptical dot shape.

 

[gordo]

Elliptical p is the suggested dotshape from industry for Harlequin user. The reason behind it is the dot link up. Basically for newspaper, it is much better if you will you use elliptical dot shape. Try to investigate the difference between the dot link up of round and elliptical dot shape.

Yes, "investigate the difference between the dot link up of round and elliptical dot shape" which is why I linked to: Quality In Print: AM Screening Dot Shapes which gives this info.

For newspaper, you say that "it is much better if you will you use elliptical dot shape" but you don't say why. In fact elliptical is the worst dot shape choice for newspaper due to the typical lpis used for this type of work.

best, gordon p

 

[BillJ]

Gordo, thanks for the clear and concise explanation.

 

[lyzan]

For newspaper, you say that "it is much better if you will you use elliptical dot shape" but you don't say why. In fact elliptical is the worst dot shape choice for newspaper due to the typical lpis used for this type of work.

If one selected incorrect angles, yes it will give you unsatisfactory results. Elliptical dot shape combine with carefully selected angles will give best result. Dot link up of elliptical is its huge advantage. Moire can be avoided by choosing appropriate angles.

 

[gordo]

If one selected incorrect angles, yes it will give you unsatisfactory results. Elliptical dot shape combine with carefully selected angles will give best result. Dot link up of elliptical is its huge advantage. Moire can be avoided by choosing appropriate angles.

It doesn't appear that you bothered following the link I gave.

The problem with elliptical dots for newspaper has nothing to do with incorrect screen angles. The dot link up that you say is its "huge advantage" is actually its biggest problem in this application.

Here's the link again: Quality In Print: AM Screening Dot Shapes

Read it. If what I wrote is incorrect then point out what is incorrect and explain why it is incorrect.

BTW, Moiré cannot be avoided by choosing appropriate angles. There is always moiré with an AM/XM screen. There are methods to minimize the visibility of the moiré - but it is still there. That is because of the inherent nature of a quadratic grid.

best, gordon p

 

[lyzan]

@Gordo

There's nothing wrong with your article. However, base on my understanding and the fact that most newspaper printers that I knew are using elliptical dot shape, I always recommends to use elliptical dot shapes.

It is less prone to ink spreads thus minimizing midtone jumps. And I am talking about the visibility of moire in the naked eyes. Without proper angles, moire in elliptical dots will be very visible such as in skintones.

Anyway, in real world, who cares? Thus, I do not debate.

 

[gordo]

@Gordo

There's nothing wrong with your article. However, base on my understanding and the fact that most newspaper printers that I knew are using elliptical dot shape, I always recommends to use elliptical dot shapes.

It is less prone to ink spreads thus minimizing midtone jumps. And I am talking about the visibility of moire in the naked eyes. Without proper angles, moire in elliptical dots will be very visible such as in skintones.

Anyway, in real world, who cares? Thus, I do not debate.

I don't intend to be argumentative however, just because most newspaper printers that you know use elliptical dots does not make that dot shape the best for their application. There could be many reasons for them using that dot shape - none of which have anything to do with what is best for them.

Elliptical is less prone to a visible midtone jump than Euclidean because it splits the jump in two smaller jumps at 40% and 60%. But both those tones are still prominent grey tones. Round dot buries the visibility of the jump in the shadows at around 78% - much less visible than 50%, 40% and 60%.

In the real world, I think it's important to know what choices one makes and why. That helps to make right choices for the printer and their customers - so I do care.

best, gordon p

 

[lyzan]

In newsprint, the dot link up in round dots made it more susceptible to midtone jumps as all corners touch each other.

 

[gordo]

In newsprint, the dot link up in round dots made it more susceptible to midtone jumps as all corners touch each other.

You might be thinking about Euclidean (round/square/round) where the dots form a checkerboard at 50%. With Euclidean you would be right.

But with round dot, the dots touch each other at around 78% so that is where the jump is - in the shadows where it is not visible.

best, gordon p