Selecting Microsoft Print to PDF or Save as PDF from the print dialog and clicking Print does not send the document to a physical printer. It sends it to a virtual PDF printer, a piece of software that accepts a print job exactly as a physical printer would, but instead of placing ink on paper, it writes a PDF file to disk. The resulting PDF looks like the document as it would have appeared on paper, but it is a new PDF, structurally different from the original. Understanding what happens during this virtual printing process explains why the output PDF sometimes behaves differently, looks different, or has different properties than the source document.
How a Virtual PDF Printer Works
A virtual PDF printer registers itself with the operating system as a printer device. Applications do not distinguish between a virtual PDF printer and a physical printer. They send the same print commands, the same page description language, and the same rendering instructions to both. The virtual PDF printer receives these instructions and converts them into PDF format instead of sending them to a physical print engine. The application thinks it printed the document. The user receives a PDF file.
The print commands sent by the application are typically in the form of a page description language, most commonly PostScript or XPS, depending on the operating system and the printer driver. The virtual PDF printer interprets this page description and builds a PDF from it. The resulting PDF is a new creation, derived from the print output of the application, not a copy of the original file. Every page is re-rendered. Every font is re-embedded. Every image is reprocessed. This re-creation is the source of the changes that can occur during virtual PDF Printing.
What Changes During Virtual PDF Printing
Font handling changes during virtual printing. The original PDF may have used embedded fonts with specific encoding. The application sends the fonts to the virtual printer as glyph outlines or as font references. The virtual printer embeds the fonts into the new PDF using its own font embedding logic. If a font was subset in the original, the virtual printer may subset it differently, potentially losing characters that were present in the original. If a font was not embedded in the original but was available on the system, the virtual printer may embed it, creating a more self-contained document.
Image quality can change. The original PDF may contain high-resolution images. The application print output may downsample those images to the printer default resolution, typically 300 DPI. The virtual printer then embeds the downsampled images into the new PDF. A 1200 DPI image in the original becomes a 300 DPI image in the output. Repeating the virtual print process on the same document compounds this loss, because each cycle applies the same downsampling to images that have already been downsampled once.
What Is Lost During Virtual PDF Printing
Interactive elements do not survive virtual printing. Form fields, hyperlinks, bookmarks, digital signatures, comments, and annotations are carried in the original PDF as interactive objects separate from the page content. The application print output renders these elements as visual marks on the page, or omits them entirely. The virtual printer receives the rendered page, not the interactive objects. The output PDF contains the visual appearance of the interactive elements, but not the interactivity itself.
Metadata may or may not transfer. The original PDF document title, author, subject, and keywords are stored in the PDF metadata dictionary. The application may send these as document properties to the virtual printer, or it may not. The virtual printer may populate the new PDF metadata from the application print job properties, or it may leave the metadata fields blank. Check the document properties of a virtually printed PDF. If the title and author are missing, the metadata was lost during the print process. The PDF Format structure of the output is a fresh creation, not a copy of the original structure.
Why Virtual Printing Is Still Useful
Despite the losses, virtual PDF printing is useful because it solves specific problems. A PDF that refuses to open in one viewer but opens in another can be virtually printed from the working viewer to create a new PDF that opens everywhere. The re-creation process discards whatever structural peculiarity was causing the compatibility problem. A PDF with permission restrictions that prevent editing or copying can be virtually printed to create an unrestricted copy. The restrictions do not survive the print process because the output is a new PDF.
A PDF assembled from multiple sources with inconsistent formatting can be virtually printed to normalize the appearance. The print process re-renders all pages through a single application, smoothing out the differences between the source PDFs. The PDF Export from a virtual printer is a lowest-common-denominator PDF that trades fidelity for compatibility. For documents where universal readability is more important than preserving every pixel of every image, virtual printing is a practical tool.
Comparing Virtual PDF Printers
Different virtual PDF printers produce different output from the same source document. Microsoft Print to PDF, included with Windows, produces compact PDFs optimized for screen viewing. Adobe PDF, installed with Acrobat, produces PDFs that adhere closely to the Adobe PDF specification and preserve more document features. Third-party virtual printers like CutePDF, doPDF, and Bullzip offer additional options such as resolution control, metadata preservation, and compression settings.
Test each virtual printer with a representative document before standardizing on one for a workflow. Print the same PDF through each virtual printer and compare the output. Check the file size, the image quality, the font rendering, and the metadata preservation. The differences can be significant. A virtual printer that produces excellent results for text documents may produce unacceptably soft images for photograph-heavy documents. Choose the printer that best matches the document type.
How to Minimize Unwanted Changes When Virtual Printing
To preserve image quality, check the application print settings before sending the document to the virtual printer. Set the print quality to High or Best, which instructs the application to send images at full resolution. In the virtual printer properties, set the output resolution to match or exceed the resolution of the images in the original document. If the original contains 600 DPI images, set the virtual printer to 600 DPI or higher.
To preserve fonts, confirm that the application is configured to embed fonts in the print output. Microsoft Word, for example, has a font embedding option in the Save settings that affects how fonts are sent to the printer. For the virtual printer, ensure that font embedding is enabled in the printer properties. WukongPDF provides PDF Printing alternatives that produce high-quality PDF output without going through a virtual printer, which avoids the quality losses inherent in the print-to-PDF pipeline.
Virtual PDF printing is a conversion process, not a copy process. Understanding it as a conversion, with the associated losses and transformations that any conversion entails, sets appropriate expectations for the output quality. When the goal is an exact copy of the original PDF, use a save or duplicate function, not a virtual printer. When the goal is to normalize, repair, or un-restrict a PDF, virtual printing is the right tool for the job.
Virtual PDF printing can also be used to create PDFs from applications that do not have a native PDF export function. An old database application, a specialized engineering tool, or a legacy accounting system may only offer a Print option. The virtual PDF printer captures the print output and creates a PDF that preserves the information, if not the original document structure.
When virtual printing a PDF that contains sensitive information, be aware that the virtual printer may create temporary files on disk during the conversion process. These temporary files may contain the document content in an unprotected intermediate format. For highly sensitive documents, use a native save or export function rather than a virtual printer.
The file size of a virtually printed PDF is typically larger than the original because the virtual printer re-encodes all content. Text that was stored efficiently as character codes may be converted to glyph outlines. Images may be re-encoded with less efficient compression. A file size increase of thirty to fifty percent after virtual printing is common.
Virtual PDF Printing is a conversion process with inherent losses. Understanding those losses allows you to use virtual printing when it is the right tool and to choose a different method when maximum fidelity is required.
The virtual PDF printer remains one of the most versatile tools in the PDF ecosystem because it creates PDFs from any application that can print. It is the bridge between the print world and the digital document world.
This article covers the key techniques and considerations for working with PDFs in this specific scenario. The methods described here apply across different tools and platforms, giving readers the flexibility to choose the approach that best fits their workflow and technical environment.
The practical steps outlined provide a clear path from the initial challenge to a working solution. Each technique has been selected for its reliability and accessibility, ensuring that readers can achieve consistent results regardless of their prior experience with PDF tools.