About the PZ zoom factor

The PDF format standard allows a "preferred" zoom factor (PZ) to optionally be specified for a particular page. This is defined as 

"The page’s preferred zoom (magnification) factor: the factor by which it shall be scaled to achieve the natural display magnification."

It is easy to misread this. This optional field is not the zoom factor which users viewing that PDF page might prefer to use when viewing the PDF. Rather it is - speaking anthropomorphically - the page's own "natural" preferred zoom factor. Where the content of a PDF page was originally downscaled during capture the PZ attribute can optionally be used to record the magnification factor which would be necessary to exactly undo the downscaling. So an A4 page scanned into an A4 PDF page would have a PZ of 100% whereas an A3 page scanned in as an A4 PDF page would have a PZ of 140%. 

The PZ factor was originally defined for use in the specialised procedure of Web Capture but is little known and rarely set. 

Disclaimer

The information above is necessarily of a general nature and will not be applicable to every case: it is intended to be used in conjunction with more specific advice to the individual client about the individual case. Contact me for advice about your case.

The information on this page about specific computer techniques is provided for information purposes only. Every reasonable effort has been made to ensure that the information is accurate and up to date at the time it was written but no responsibility for its accuracy, or for any consequences of relying on it, is assumed by me. You should satisfy yourself, before using any of the techniques, software or services described, that the techniques are appropriate for your purposes and that the software or service is reliable.

This page was lasted updated in January 2025. Disclaimer