PDF stands for Portable Document Format, which was created by Adobe Systems in 1993 as a file format designed for document exchange. Independent of the operating system, hardware and application software, it is used to represent documents that are two-dimensional. Every PDF file comes with a full description of a fixed-layout two-dimensional document, which includes 2D vector graphics, images, fonts and text. In addition to these basic facts, there are other interesting details about it including the dimensions of a PDF page.
PDF Page Dimensions
Measuring the actual size of a PDF page when set to a 100 percent view, it is 8 inches wide and 10 inches long. However, this measurements are about to change when the view is set to a larger or smaller size. In terms of structure, each file can have eight different kinds of objects, which include strings, numbers as well as Boolean values. Aside from these, you can also find the Null object, arrays and names. You can also find streams, which are made up of large volumes of data. Each file can have collections of names arranged by names, which are called dictionaries.
Additional Facts and Other Interesting Details
A device-independent Cartesian coordinate system is used to produce PDF graphics. The primary purpose of this is to describe the page’s surface. A matrix is then used by a PDF page description to skew, rotate or scale graphical elements. As of version 1.6, a PDF file features a total 24 different graphics state properties, the most important of which are the key transparency component called the alpha constant, the color space as well as the clipping path. In order to determine the coordinate system, it also has the current transformation matrix.
A PDF file is designed to support different image filters, the most important of which are the FlateDecode, DCTDecode and RunLengthDecode. Aside from these, you can also find other general-purpose filters like the JPXDecode, JBIG2Decode as well as CCITTFaxDecode. In page content streams, the text is represented by two major elements, namely the encodings and the fonts.
Based on the standards set under the International Organization for Standardization or simply ISO, the PDF has several subsets. One of these is the PDF/UA, which is for PDF files, specifically those that are universally accessible. Another one is the PDF/E, which is intended for the exchange of drawings in engineering. For graphic arts and printing, the appropriate subset is the PDF/X.
Every PDF file is comprised of raster graphics, text and vector graphics. Raster graphics are for images and photographs, while vector graphics are for designs and illustrations, specifically those that are made up of lines and shapes. Some of the most notable typefaces significant to PDF documents include Helvetica, Courier and Times.