Sep ctrl dot pattern.

[Mac-S]

Hi everybody.

I have a Sieko V64s and the latest version of Onyx.
I have tried to build a profile with the new sep ctrl. " dot pattern " which according to Onyx should be better than regular stochastic rasters. To me it seems to be just another way of ink restricting, without any measurement at all. which makes it less accurate the way I see it.
Normally I restrict the ink to meet euroscale target densities, but since there is no measurement I don't know how to do that anymore. Also I don't know how to"bend" the curves.

I have noticed some improvement in the darker areas though, but the highlight areas loose all detail when using sep ctrl. compared to my old profile.

Does anybody have some good suggestions, or rules of thumb.

[MarcoRoos]

Hi Mac,

SepCtrl (SC from now on ;-)) is indeed a new way of restriction ink channels. The best way to use it is to take the following steps:
1. go the Media Manager and configure a new workflow, in the workflow option tick the "Print test print" option of the ink restrictions step and save the workflow (this will enable you to print a test file after setting the ink restrictions by using SC.
2. in the SC tool you can easily modify curves by selecting "Spline" in the upper left corner of the dialog. The default setting is line and this indeed doesn't allow you to create bended curves.
3. Now you can draw curves by adding a node (click on the curve) and drag the node to where you want it. Adding a node will also add a percentage to the list on the right side of the dialog, this allows you to put more accurate values in.
4. For light inks I would start with a curve for LC that tops at around 50% at 50% coverage (exactly in the middle of the graph). create a node a 70% and set the value to 0.
5. Select the Dark Cyan color from the drop-down menu. Select "Spline". Start with the dark cyan curve at 40%. Set the 50% coverage to 45% density (the curve should 'start slowly' now and becomes steeper after 50%.

I agree this probably doesn't sound clear but imagine two curves blending into each other.

We use it a lot here since we are profiling a lot of different printers for various R&D departments of printer manufacturers and we got great results.

Another option for you might be to use the Enhanced Error Diffusion dot pattern instead of Stochastic. The difference in smoothness is significant.

[Mac-S]

@ MarcoRoos ( from colorconcepts ).
I will try it one of these days.

Did you find these settings by trial and error, measurements, experience or did you get the suggested values from Onyx or a printer manufacturer?.

[MarcoRoos]

(11-02-2009 12:25 AM)Mac-S Wrote:  @ MarcoRoos ( from colorconcepts ).
I will try it one of these days.

Did you find these settings by trial and error, measurements, experience or did you get the suggested values from Onyx or a printer manufacturer?.

A combination of everything. There is no way to find them by measuring, so trial and error and experience helps a lot. We were hired by a large printer manufacturer and ONYX to work on this particular project.

I also ran a project in South Africa for dye sublimation direct-to-textile printers with light inks. This worked out really well with this tool, although it could be a lot easier and better by having a measurement option.

I am working on this with ONYX to make it a lot easier. Any feedback from your side will be highly appreciated!

Thanks!
Marco

[Douglas]

(10-07-2009 01:31 AM)Mac-S Wrote:  " which according to Onyx should be better than regular stochastic rasters. To me it seems to be just another way of ink restricting, without any measurement at all. which makes it less accurate the way I see it.

I am very sorry someone at Onyx told you this about the SC. It "is" the stochastic dot pattern, not a new dot pattern.
It was implemented as an OEM dot pattern to avoid a complete rewrite of the Onyx 7 Media Manager. This allowed us to easily plug in a curve editing tool for ink restricting and VarDot curve manipulation. The primary purpose of SC is to allow the user to freely adjust transitions and ink separations (light and dark inks) and tweak VarDot.
There is a white paper located here that describes SC in considerable detail.
http://www.onyxgfx.com/newsletter/Separa...l_Rev3.pdf

Unfortunately, the only current way to measure is to add a "Print test Image" step to the Media Manage workflow and use the Spot Measure Tool.
Alternately, I just do multiple calibrations so I can use an X-rite Isis or DTP 70 and then later delete the calibrations I don't need from the Media Library.

As the print lab manager, being able to measure more elegantly is currently my top priority and I am pushing to have an improved solution going forward.

Regards,
Doug