Efficiently creating varnish or white background (requires at least v9.1)
In pdfToolbox 9.1, the "Shape" feature has been enhanced. This article shows how to take advantage of the enhancements when creating a varnish or a white background. The two attachments below provide the sample PDF and the pdfToolbox Library containing the fixups used in this article.
When creating a partial varnish it is often desirable to derive the area where varnish shall be applied from actually printed content. At the same time, mostly in order to compensate for less than perfect registration of plates or print heads, it is usually necessary that the varnish extends slightly, maybe by a millimeter or two, beyond the printed content area, to ensure that printed content is always varnished. The fact, that some small area where nothing is printed also receives varnish, is typically not considered a problem.
Along the same lines, but usually in the other direction, a white background may have to be created for printing on transparent substrate – but as the background shall not become visible as such, it needs to be shrunk by a little bit to pull back from the border of the print content area.
Both requirements can now be met very easily by the extended "Shape" feature, using the "adjust size" setting. This setting was already available for shapes based on page geometry boxes or a custom box but now can also be used for shapes derived from tracing page content or from existing vector paths.
In addition, a new setting "Reduce shape to outer borders" makes it possible to include 'holes' inside print content areas, which can be very handy for the generation of a white background (see example below). Extending/shrinking shapes and 'reduce to outer border' can be freely combined with each other and any of the other options.
Create shape parameters for "From vector paths" option, with highlighted "Adjust size" settings:
Create shape parameters for "From tracing page content" option, with highlighted "Adjust size' settings:
"Reduce shape to outer borders" setting:
Sample file (see above for download):
Sample file (see above for download, enlarged detail):
Varnish applied to all page objects based on their vector paths, after applying "Varnish over print objects +2mm (vector)":
Varnish applied to all page objects based on their vector paths (enlarged detail):
White background derived from all page objects based on their vector paths, using only the outer border of all paths, using "White backing under print objects -1.5mm, based on outer border (vector)":
White background derived from all page objects based on their vector paths, using only the outer border of all paths (enlarged detail):