Basic Principles of Working with PDF Files
The main difference between a PDF document and any other text file is formatting. The formatting that was set when the file was created and does not depend on external factors is saved here. This means that no matter what device or operating system a PDF file is opened on, it will always look the same. To make sure that a file is displayed well on any device, it is recommended to save it in PDF format. Any PDF combiner allows you to download offline version, regardless of which screen and program you are viewing the file in. In addition, printing documents becomes more convenient. All elements of the document will remain in place; the text will not be able to go off the sheet, and the numbering of the text will remain exactly the same as on the device. Is this what you want to achieve? Then keep reading this post — we will talk about what a portable document format is, its display features, as well as the basic principles of working with PDF files.
Portable Document Format — What Is It and What Are the Types
Portable Document Format (PDF) is a universal cross-platform open format that allows you to display an electronic document in any operating system, in any program, on any device in the same form in which it was created.
PDF files can be of two types:
- Text — the main distinctive feature of a text file is the ability to select individual words and phrases;
- Raster (scanned) — the principles of working with such files will be somewhat different. If the original, (almost) error-free text can be extracted from text files, then scanned ones will have to be recognized.
PDF — Principle of Operation
Since 2008, PDF has become an open format, which has allowed developers to create PDF readers, converters, and other useful things without problems and additional costs. The development of OCR has led to the fact that the previously unchanged PDF document can now be edited and updated — line by line or within paragraphs.
Even though PDF is a text format, in digital form these letters, words, and sentences do not actually exist; they are “drawn.” Content is stored as streams, such as text, images, and vector graphics. PDF does not contain the typical DOC words, lines, paragraphs, and tables. There are no letters as such in the format, but there are character codes. Such codes with the same characteristics are combined into groups according to the type and size of the font. This font determines how a character should be displayed in a document by mapping the character code to a glyph, a set of drawing commands. Another difference from a regular text document is that PDF objects exist in three dimensions. The Z coordinate is used to estimate the depth of an object on a page because text can be on top of an image or vice versa. The text in a PDF document is like a “bag of letters” that needs to be displayed correctly in certain places in the document with appropriate formatting.
Why Is It So Difficult to Edit the Text in PDF?
PDF was not originally intended to be modified in any way. The key advantage of the format is its security, identical display on any device, and a convenient way to exchange information. Of course, this brings one serious disadvantage — problems with making changes, searching in the text, and comparing documents. Although you cannot do it directly in a file, you can use special programs for this purpose.