Vanishing/Gradient Problem

[osmond]

Hello,

Im having trouble with vanishing/gradientt, applies to any application and file format. see attached. on the left side is how the vanishing looks like in our film. on the right side is my goal... how can I achieve a smooth(right) vanishing in our output? we always end up with staggered vanishings(Left side).

we're using Dolev 800v with PSM 7.1 rip. is there any settings that we need to set to achieve a smooth vanishing?

Thanks in advance.

 

[pcmodem]

It could be a calibration issue. If you are trying to adjust every percentage you will end up with the stepping you see on the left and to fix the problem you would need to simplify your calibration. The calibration should not contain a lot of points.

 

[gordo]

Hello,
Im having trouble with vanishing/gradientt, applies to any application and file format. see attached. on the left side is how the vanishing looks like in our film. on the right side is my goal... how can I achieve a smooth(right) vanishing in our output? we always end up with staggered vanishings(Left side).
we're using Dolev 800v with PSM 7.1 rip. is there any settings that we need to set to achieve a smooth vanishing?

Thanks in advance.

If this is negative film, then the shadestepping may not show up in the presswork. You'll often see this problem with negative film just because when light passes through the halftone dots it exaggerates the appearance of tone differences - but the problem does not appear in the pressork.

You could also lower the lpi of the halftone while keeping the dpi of your output device the same to see if that helps. If it does then you need to look at the grey levels setting in your RIP or, if you have it, the Turbo Screening settings.

best, gordon p

 

[Katlynn]

PSM gradient settings

PSM gradient settings

Did you already check out the gradient settings within PSM 7 itself? This helped with some gradients when we were working with PSM 7 with a Dolev 400.

 

[Chris Halt]

Are you including bitmap and vector in your "any application and format" statement? Creating a vector based gradient in Illustrator, Quark, InDesign, etc. can produce stepping. Bitmap gradients (i.e. PhotoShop) generally speaking do not. If this began as a vector gradation some apps can rasterize them directly without having to resort to a PhotoShop conversion. A variety of factors: resolution, % degrees of separation in the start & stop points of the gradient (the fewer the more difficult it is to create a smooth transition), understanding file creation best practices, all contribute to achieving smooth grads. We are able to reproduce perfectly smooth graduations using bitmap images created in PS, output @ 2400dpi CTP. It's not unusual for us to recreate gradients in PhotoShop to replace poor customer supplied artwork. Sometimes we simply rasterize the supplied grad vector artwork at a very high resolution and update it in the doc, then process as normal.

 

[osmond]

Pcmodem - we calibrate the dolev using onlv the default settings, by 5,10,15,20...etc What is yours?

gordo - it regularly happens in single color run-on negative and positive. if its full color and the vanishing is in single color part only it also shows. we don't hve the turbo screening .

kathlynn - grey/gradient levels settings is at default

Chris Halt - both bitmap and vector and from any application.

can anyone can share me a setting in my gradient/grey settings that we could try.

Thank you very much.

 

[WiseGuy]

This was an issue from way back in the old days when I was a support tech for Aldus Freehand. Assuming you don't have any settings wrong on your RIP... here are the things that will cause gradient banding.

1. Low Linescreen frequencies. A 90lpi setting will cause more banding than a 150lpi setting. The higher the LPI the smoother the result.

2. Gradient density range and size. You will get smoother gradients going from from 100% black to 0% black over a 3 inch area than going from 100% to 50% black.

3. Lastly, output resolution. The higher the better.

These are the three factors that will negatively affect your output. I use to have a gradient calculator that you could plug in some values and determine the number of gradient steps, but that was so long ago, I can't remember the formula. But there is no magic. It's all math.

I hope this helps!
Michael Reiher
Dynagram

 

[kyle]

A 90lpi setting will cause more banding than a 150lpi setting. The higher the LPI the smoother the result.

As long as the screen tiles in a RIP are well made, higher line frequencies generally increase banding (above a certain threshold). At a given resolution, a lower lpi yields a larger dot, and therefore more possible sizes (levels).

As an extreme example, consider 2400 dpi, 45 degrees, 1,697 lpi. There could only be three levels because the dot is so small: white, 50% gray (a checkerboard pattern on the plate at the smallest possible scale), and black. As you spread the dots farther apart (decreasing lpi), the number of possible levels increases.