1 PDF Overview
PDF (Portable Document format) is a structured document format. It is well-known American publishing and image processing software company Adobe company first released in 1993 (1.0 version), Adobe launched the company the same year, the corresponding software product line to support Adobe Acrobat 1.0; then Adobe company for its revision and upgrading of the released 1994 version 1.1 and introduced a software product line to support Adobe Acrobat 2.0 and 2.1 version. PDF version of the latest version 1.2 in November 27, 1996 release, the corresponding support software product line also upgrade to Adobe Acrobat version 3.0. International Organization for Standardization by the end of 1997 has already begun planning to PDF accepted as international standards.
1.1 PDF and PS Comparison
Page Description Language PS (Postscript) by the Adobe company has a de facto industry-standard printing. It describes the layout fine, in the current field of printing is still dominant. PDF evolved from the PS, in regard to the description of the page they are almost identical and similar to the description of methods. PDF and PS using the same shading model (Imaging Mode) to the performance of text and graphics. The same with the PS language, PDF page description of the command is selected to map region coloring pages. Coloring can be letters regional profile, the definition of a straight line and curve of the region, as well as bitmap; color shading can be arbitrary; any graphics on the page can be cut into other shapes; the beginning of the page is empty, a variety of command Rendering to a different page, the new graphics are opaque and can be covered by the old graphics.
In spite of this, PDF and PS in comparison, there are very different. Mainly in the following aspects:
PDF files can contain objects such as interactive hyperlinks, interactive forms and so on. And PS no.
PDF is a file structure, while the PS is a programming language. PDF has therefore higher than the PS efficiency.
PDF allows the definition of the strict structure of application objects which random access, while the PS only sequential access. For example, a PS file to access the first 100, we must first explain their pre-order after the 99 to find the first 100, and in the PDF of each page are the same access to fast.
PDF contains the specifications for font size font description for the font when font does not exist simulation (rather than a simple character substitution), to ensure the consistency of the document shows.