As many of you already know, the Signature Group editor in Workbench can import a variety of imposition signatures. However, we have encountered some files which contain impositions that are not as accurate as the numeric precision which is used in the file. This inaccuracy varies and and can often result in imported signature pages not grouping into grids, or grouped pages that are unable to be paired.
To compensate for that, the ability to round numeric values has been added to the importing of signatures. The precision in this rounding varies depending on how you import your signatures.
Note: Blackmagic stores all dimensions and positions in inches. So rounding precision is in reference to values in inches.
Importing with Selective Import Off
When Selective Import is off, dimensions and positions in the signatures are rounded to 4 decimal places before and after an attempt to group pages into grids.
Importing with Selective Import On
When Selective Import is on, the Signature Import Filter dialog is presented to let you decide which signatures you would like to import, with the option to perform a number of operations on them when importing. The Inclusive check box you see here deals with the rounding precision when importing.
When Inclusive is on, values are rounded to 3 decimal places before and after grouping.
When Inclusive is off, no rounding is performed at all.
Rounding can work for or against us, and Inclusive is certainly no guarantee that the pages will group and pair. Excessive rounding can actually result in pages not grouping or grouped pages not pairing when, for example, the inherent inaccuracy of the file is magnified, rather than reduced, by the rounding.
If pages are not grouping or pairing when importing, try the different options outlined above. If nothing seems to help, here’s a check list to go through. First, I would set the display unit of the Serendipity Client to points to increase the precision displayed. Also bear in mind that the Signature Editor only displays values to 4 decimal places.
Page Grouping Check List
- For pages to be grouped in a row, they have to have the same y position.
- For pages to be grouped in a column, they have to have the same x position.
- For pages to be grouped at all, they have to have the same dimensions.
Page Pairing Check List
- For pages in a grid to be paired vertically, there must be an even number of rows.
- For pages in a grid to be paired horizontally, there must be an even number of columns.
- For pages in a grid to be paired, head directions of adjacent pages (pages to be paired) have to be the same.
- For pages in a grid to be paired, every second row gap (pair vertically) or column gap (pair horizontally) must have the same dimension. In strict pairing (by using the Pair Pages button instead of the Pair Vertically or Pair Horizontally button) there must be no gap between pages you want to pair.
We will be looking into more intelligent methods for inaccuracy compensation for future versions of the Serendipity Client, but for now at least you know what goes on behind the scene.
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