HP LaserJ et Print Driver HP LaserJet EMF Spooling

Security Level: Customer Verbal Use Only Date Written/Updated: September 23, 2005 Document Summary When printing with the HP LaserJ et Unidrv-based drivers customers may see spool file sizes that appear to be abnormally large.

Issue Statement: EMF Spool File Size and Unidriv Printing

Microsoft Windows Graphics Device Interface (GDI) does not compress raster data when processing and generating Enhanced Metafile (EMF) spool files. This is seen in multiple applications. Microsoft Word documents, for example, which contain screen shots (bitmaps) that when stored as part of the document, the bitmaps are compressed, but when printed, are not compressed. The GDI compression issue is even more problematic with Adobe PDF files which contain gradients. Because GDI does not have a method for describing gradients, the gradient is broken into small pieces of raster (bitmap) data which are passed through the pipeline uncompressed and lead to extremely large spool file sizes.

So why does this only seem to happen with the HP LaserJet printer Unidrv-based drivers? All page manipulation features in the HP Unidrv/Pscript-based drivers are handled by a print processor that is shared across all Page Description Languages (PDLs). HP uses a proprietary print processor so we can implement many of the advanced features in our drivers such as collate, N-up, scaling, advanced paper handling, watermarks, Postscript pass-through disable, and rotate. All print processors depend on the EMF spool format to perform any advanced page manipulations features, and therefore, to utilize the features above, print jobs must be spooled to EMF.

The HP Commitment HP is committed to working with Microsoft and to identifying alternative approaches to addressing this situation.

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