PDF: How it works

The PDF is designed to keep up with today’s fast-paced and highly demanding work world. Portable Document Format files are safe in online activities because these are “Read Only” files that cannot be altered without leaving the Electronic foot print .This makes the PDF safe since it satisfies the legal requirements to stand up in a court of law.PDF file system was introduced by the Adobe systems in 1993 to make a safe file transfer in electronic media.PDF is equipped with Compression Algorithms which is used for compressing the graphics or images in the files. Algorithm makes the PDF file smaller and portable. TIFF, JPEG, GIF files etc used in web can be easily altered without leaving the electronic footprint, but it is difficult to manipulate PDF and the owner can make complaints if a manipulation is noticed.

PDF files are considered as safe files since the concept behind it is non editing nature and protection. It is used to share official files, business documents, online journals e- publishing etc. It is safer than any other files like Word, TIFF, JPEG, GIF etc since it leaves an electronic foot print during manipulation. So the owner of the file can easily prove the identity and copyright of the document. Even though, the PDF is safe, there are possibilities of manipulation if a tricky person wishes to do so. An ordinary person will not try to do so because of its consequences but still there are possibilities. Two ways to manipulate PDF are:

1. Scanning the PDF file and using the image – The downloadable PDF file can be scanned to make an image. Using the Photoshop, the scanned image can be manipulated such as removing the watermark, removing the copyright statements, publisher’s name etc. But the scanning process is an optical activity and without leaving the electronic foot print, it is impossible to take the document. The data regarding the compression of the PDF will be available in the hard disk of the manipulator’s computer which can be retrieved even if the computer is formatted.

2. File conversion – Using Converter softwares, it is possible to convert PDF files to Word files or other forms. Usually this is done for personal use to read or reference. The policy of such softwares strictly warns about the use. So such converted files cannot be published in electronic media or print media without the permission of the owner.

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How to create PDF?

Creation of PDF is easy. In one method, the physical paper file is scanned first and the image thus obtained is saved in PDF. Such files are known as Scanned PDF files. The most commonly used method is the use of PDF writer softwares. This Native Portable Document Format application helps to convert any formats such as word to create a PDF files through electronic processing. Common files such as word files, excel files, power point etc can be converted into non editable files.

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Technology of PDF

PDF uses three technologies for converting the files. These are:

1. Post Script page description

This is the page description language run in an interpreter to generate the PDF image. This programme can handle ordinary formats as well as if and loop commands. The Post Script code is generated from a PostScript source file. The data output from the PostScript code are then collected and compressed into a single file. So that the fonts, layout etc of the file remains intact.

2. Font Embedding

This system allows the fonts to travel with the document .In the PDF, the font is the description of a Digital typeface. It can be either a description of the typeface or represents embedded font file. The standard Fonts include Times new Roman, Courier, Helvetica, Symbol etc.

3. Storage system to keep the data in a compressed form

Compression Method

PDF files are compressed files having large quantity of data. For example, a word file 8 ½ x 11 letter size is around 1000kb size while its PDF version has only 28-30 kb size. Approximately 25% size reduction occurs during compression.This compression is helpful to upload large quantity of data in mails and Web. Compression method helps to reduce the space in hard disc use and transmission bandwidth.

Security and Benefits

PDF files incorporate large amount of information. You can also include multimedia files to make them more interactive. The files can be encrypted with passwords, digital signature etc so that only the user can open the files. The Compression Algorithms make PDF more flexible and compatible in multiple platforms. Using the PDF creator software, you can make secure files with professional appearance. PDF files can be easily shared through the net without the anxiety of piracy since it is electronically created leaving an electronic mark. For a document to be admissible in the court of law, it must be in a format that cannot be altered by the user. Ordinary image files will not leave an electronic foot print, so alterations are possible. But the PDF files should be scanned before alterations. This leaves an optical mark in the scanner so that the original data can be retrieved.

Reading PDF

Adobe Acrobat Reader software is used to read PDF which is a freeware that can be easily installed in the computer. It can be downloaded from the internet.