The PDF imaging model as defined by version 1.6 of the PDF specification doesn't have native support for shadows, and therefore the PDF specification doesn't have a direct way to specify them. Quartz works around this by creating two representations of the drawing of a shadowed object when it creates a PDF document. One representation is recognized by Quartz when it draws such a PDF document but is ignored by Adobe Acrobat and PDF processing tools that are not based on Quartz. The second representation is a rasterized representation of shadowed object drawing that is used by Adobe Acrobat and PDF processing tools that are not based on Quartz.

In versions of Mac OS X prior to version 10.4.4, Quartz shadows are recorded into a PDF document using an extension to the PDF specification that is recognized only by Quartz. On these systems, copying PDF data to a pasteboard and using that data with other Mac OS X applications that draw PDF data using Quartz will display and print the shadow. However, for the PDF documents produced by these earlier versions of Mac OS X, Adobe Acrobat does not display any Quartz shadows graphical elements are drawn as if there were no shadow specified.