OptiRange allows applying a minimum and maximum dot on the calibration curves to avoid losing dots on Flexo plates. Nexus and ArtPro allow you to access and define OptiRange. This article is to help you understand it better, in addition to the Nexus manual.
How to access
Open a new document and then go to the ArtPro menu bar > Prepress > Screening > Screening.
In the new Screening window, go to the Extended Nexus tab and click the OptiRange Set... button.
The name of the Set... button changes to Change..., if OptiRange has been set already.
Clicking the Set... or Change... button will invoke the following window. You can define OptiRange in this window.
You can access the OptiRangesettings window, using either of these task:
Assemble Separation task (Nexus Basic RIP)
Rasterise Separations task (PDF RIP)
Click the Set Symphony Control button and go to the OptiRange tab.
How to Interpret and Configure
One of the confusing aspects can be the different units that are being used. The Min/Max value is specified as a tint percentage value (i.e. in the range 0 - 100), while the Start/End value is a "system value" in the range 0 - 255. So for example, a Sysval of 10 is equivalent to a percentage value of (10 / 255) * 100 = 3.9%.
Below are a few examples that illustrate what the OptiRange Settings window allows you to accomplish. Additional information on the elements in the user interface can be found in the Nexus manual.
Min (Dot %): 2 Start (Sysval): 10 Action: Drop
This should be interpreted as: Any tint less than Sysval 10 is dropped (i.e. is not printed). Output 2% at Sysval 10/255 or 0% for anything less.
Max (Dot %): 98 Start (Sysval): 245 Action: Solid
Should be interpreted as: Any tint greater than Sysval 245 is made solid (i.e. 100%). Output 98% at Sysval 245/255 or 100% for anything greater.
Min (Dot %): 0.2 Start (Sysval): 10 Action: Hold
Should be interpreted as: Any tint less than Sysval 10 is held at the lowest printable dot (i.e. is printed). Output 0.2% at Sysval 10/255 or less.
Max (Dot %): 99.5 Start (Sysval): 245 Action: Hold
Should be interpreted as: Any tint greater than Sysval 245 is held at the lowest printable dot (i.e. is printed). Output 99.5% at 245/255 or greater.
How to define
Drop is generally used for the highlight end and Hold for the shadows.
A way to find out which settings are optimal for your press and substrate is for example by sending a file like below to the RIP and through the press, without applying any OptiRange. You then measure the result and adapt the OptiRange settings accordingly.
For example, if you conclude that dots smaller than 2% don't translate well onto the printed material, you can decide to drop them. If you conclude that a dot size of 98% gives a better result than printing a 100% solid area, you can decide to hold the dot size of 98% at the corresponding Sysval.