Point Shape

[Andrei83]

Hello, the shape of the point on the plate is not smooth, the edges are torn with notches. Why is this happening and is it normal??? How will this affect the print run? Lineature 175. The resolution on our CTP is 2400-2540.

 

[gordo]

Hello, the shape of the point on the plate is not smooth, the edges are torn with notches. Why is this happening and is it normal??? How will this affect the print run? Lineature 175. The resolution on our CTP is 2400-2540.

Looks normal. What RIP are you using?

 

[Andrei83]

I don't know what kind of rip we have. Ctp luxel T 9500

 

[gordo]

I don't know what kind of rip we have. Ctp luxel T 9500

The screening method (in the RIP/workflow) defines the shape of the halftone dots. That’s what the CTP images. The dots look well imaged.

 

[cementary]

The dots look well imaged.

If this looks well then what shape do you think it is? Certainly doesn't look like ellipse to me

 

[Macmann]

Reminds me of the Harley Davidson logo
Perhaps Gordo was speaking to the sharpness of the dots and not the shape?
Those are odd indeed.

 

[gordo]

Reminds me of the Harley Davidson logo
Perhaps Gordo was speaking to the sharpness of the dots and not the shape?
Those are odd indeed.
View attachment 290763

Yes, I was referring to the sharpness of the dots and not their shape. To me that rules out the CTP as a problem - assuming that there is in fact a problem.

Here's some dots straight out of a RIP.

Download and look closely (at least 200%). Look familiar?

The job of the CtP is to image the dots that exit the RIP precisely. The dots on the plate should look almost identical to the dots that exit the RIP.

 

[johnny_jay]

Could the shape be heavy elliptical?

 

[cementary]

Here's some dots straight out of a RIP.

Eucledian 1200 dpi?

 

[gordo]

Eucledian 1200 dpi?

I don’t think that the OP’s question was about the dot shape but about the jagged perimeter.
It also appears that the OP has left the building.

 

[cementary]

I don’t think that the OP’s question was about the dot shape but about the jagged perimeter.
It also appears that the OP has left the building.

True, i just wondered if this shape is due to lower input resolution

 

[gordo]

True, i just wondered if this shape is due to lower input resolution

The shape of the dot in a flat tone area is not much affected by the resolution of the input file nor the output device resolution.
The jaggedness of the dot's perimeter on the other hand will be more jagged when imaged at a lower output resolutuion. I.e. the dots of a 1200 dpi output bitmap will be more jagged than those of a 2400 dpi output dpi.

On the left is a 175 lpi round dot at 1200 dpi and on the right the same tone/lpi/round dot shape imaged at 2400 dpi:

 

[johnny_jay]

I asked about shape to try and recreate. The attached is heavy elliptical saved out of Prinergy 2400 dpi, 175 line screen.