MaxSmoothness, MinSmoothness (user params)

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP

With the introduction of PostScript Language Level 3 and PDF version 1.3, it is possible to construct vignettes using Shaded Fills. There are a number of controls available to impact the quality of these Shaded Fills and one which is particularly important is the smoothness setting.

Smoothness essentially controls the number of steps used to produce a vignette. Some applications set smoothness to a value which will not produce good results. In this case, vignettes are constructed in a way which reveals very noticeable banding. Typically, the creating application (usually Adobe Acrobat Distiller) can be set to use a more sensible default value, however this can be difficult to implement for all creators of PDF files. For this reason the user parameters MaxSmoothness and MinSmoothness have been created to override problematic smoothness settings.

The MaxSmoothness and MinSmoothness user parameters allow Harlequin RIP users to set sensible override values.

A typical implementation is shown below. This code can be implemented in a page feature or as part of the code in HqnOEM.

MinSmoothness can be set in a page feature or HqnOEM. However, this would not be suitable for MaxSmoothness as it would always be overridden by the Minimum shaded fill levels option in the page setup, and anything in a page feature would override the setting in the GUI, causing some confusion.

<< /MinSmoothness .001>> setuserparams

The MaxSmoothness param sets a limit which controls the minimum number of steps that can be used in constructing a vignette. This is important in ensuring vignettes do not have banding.

There is an extra divide by 2 when calculating the MaxSmoothness value from the number entered into the GUI for Minimum shaded fill levels . The default value has also changed to 256 thus the calculation is 1/256 x 1/2. Any non-default values configured in the GUI are preserved during migration

MinSmoothness sets a value which reduces the risk that the smoothness can be too fine and thereby affect rendering time.

These users parameters limit the numeric value passed to the setsmoothness operator in PostScript and the /SM ExtGstate key in PDF.

The default values for these are not likely to have any positive effect on the rendering of most files. OEMs or users must implement other values to have these new parameters impact their workflows.

The default values are:

MinSmoothness = 0.0002

The MaxSmoothness value is product-dependent and OEMs are advised to determine and set a suitable value for themselves.