printers supporting those colors. XPS supports HD Photo images natively for raster images. The XPS format used in the spool file represents advanced graphics effects such as 3D images, glow effects, and gradients as Windows Presentation Foundation primitives, which printer drivers could offload their rasterization to the printer in order to reduce computational load if the printer is capable of rasterizing those primitives. Comparison with PDF Like Adobe Inc.'s PDF, XPS is a page description language using fixed-layout document format designed to preserve document fidelity, providing device-independent document appearance. PDF is a database of objects that may be created from PostScript or generated directly from applications, whereas XPS is based on XML. Both formats are compressed, albeit using different methods. The filter pipeline architecture of XPS is also similar to the one used in printers supporting the PostScript page description language. PDF includes dynamic capabilities purposely not supported by the XPS format. There are many resources for converting from XPS to PDF and some for converting from PDF to XPS. A method often suggested is to open an XPS file in a program with printing capability, and then "print" to a virtual PDF printer such as Microsoft Print to PDF, with a similar procedure to convert from PDF to XPS. Viewing and creating XPS documents Windows Vista and later supports both creating and viewing XPS. In addition, the printing architecture of Windows Vista uses XPS as the spooler format. Apps can create XPS documents by printing to XPS Document Writer, a virtual printer that comes bundled with Windows. These files open in XPS Viewer, an optional component that comes with Windows Vista and later. In Windows Vista, XPS is hosted within Internet Explorer, but in subsequent versions, it is a standalone app. Both versions support digital rights management and digital signatures. Windows 8 also comes with an app called "Reader", which reads XPS and PDF files. The .NET Framework 3.0 installer for Windows XP also adds the IE-hosted XPS Viewer, as well as XPS Document Writer. Since then, Microsoft released the XPS Essentials Pack for Windows XP, Server 2003, and Vista, which includes the standalone viewer, an IFilter plug-in that helps Windows Desktop Search index the contents of XPS files, and another plug-in for Windows Explorer to help generate thumbnails for XPS files. Installing this pack enables operating systems prior to Windows Vista to use the XPS print spooler instead