What’s the Difference Between PDF Rendering and PDF Viewing?

Like any technology, PDF comes with a new set of jargon terms. It’s unavoidable to some degree, but never fear! We’re here to help. Two terms that get thrown around a fair bit when talking about PDF are rendering and viewing.

First up, it’s helpful to talk about the nature of the Portable Document Format (PDF). It’s very common — albeit potentially misleading — to hear it discussed as a kind of electronic “final format”, or as “electronic paper”. With that sort of language sounds like we are describing a format that is designed for displaying polished, attractive documents — or, in other words, a display format. This is what can make things a bit confusing, as the truth is more complicated.

Believe it or not, PDF isn’t a display format, as such. It is actually a container for content that includes information about how to organize and lay out that content. Behind the scenes, PDF code actually looks a bit like spaghetti, with angled brackets aplenty.

In order to display the contents of a PDF file, it first needs to be rendered into an image (i.e., display) format. There are two main approaches of encoding image information, known as rasterizing and vectorizing. Each raster (or bitmap) file contains a detailed set of instructions that specify exactly what goes in each pixel of the image. By contrast, a vector file contains instructions about how to draw the image. For example a vector image might include instructions that tell the rendering engine to draw a straight line in X color of Y length, turn Z degrees and repeat the line.

Using Debenu Quick PDF Library’s PDF Rendering SDK, it’s a fairly simple matter to render PDF content into various image formats. Once PDFs have been rendered, the resulting images can be viewed, saved, printed or discarded.

For the purposes of this post, however, the most relevant of these is viewing. Using something like our Debenu PDF Viewer SDK add-on, you can build a complete viewing experience around rendered PDFs. The viewer can then be used to view, navigate and interact with PDF documents. Some PDF viewers, including Acrobat and some of those created using Debenu Quick PDF Library (and the Debenu PDF Viewer SDK add-on (allow users to make changes to PDF documents. In such cases, what actually happens behind the scenes is that the viewing software transmits these changes. When the file is saved, changes are transferred to the saved PDF rather than just updating the rendered image of the PDF.

So, in short, rendering a PDF means turning it into images that can then be displayed; viewing is what we call it when the rendered images are actually displayed. This being the case, all PDF viewers must be built on top of rendering functionality, although PDFs can also be rendered for printing or saving in the desired image format.

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One Response to What’s the Difference Between PDF Rendering and PDF Viewing?

  1. Pingback: How PDF files are displayed - Debenu Knowledge Base

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