What is Dejavu and how to open it?

Paper books are increasingly sold in the form of collector's publications, and publishers are seriously thinking about the transition to electronic distribution of books. Readers are already available books in digital form. However, to comfortably read the next book, you will have to install on your computer special programs for reading various formats. What is Dejavu (DjVu)? This is just one of the formats of electronic books. It is used So often it will not hurt to learn about it better.

First of all, find out what the differences between DjVu and other formats are. Most digital text formats are created using text recognition when scanning (with possible subsequent editing). The Déjà vu format is a scanned image of the source file. Contains two layers - a text layer (to facilitate searching by text) and a design layer that preserves all the small details of the pages.

DjVu was created to fully copy books with accurate Transfer of the slightest strokes and conventional signs, which makes it irreplaceable in the scientific field. Before the world learned what Dejavu was, ancient books were stored in databases as a set of images of large size. The use and viewing of such books were inconvenient, and when recognizing the text their scientific value was lost.

No less useful format was to scan the technical literature. All formulas, even the most non-standard and sometimes written by hand, are displayed perfectly, as if you were reading a paper original. As a rule, DjVu books occupy a very small volume on the hard disk, thanks to a special compression technology. The sacrifice brings the number of colors (usually reduced to 2) and background images that do not carry any meaning or have no value for the reader.

Having met with a book in this format, you first need a program for reading - Dejavu Reader. It takes a few megabytes and does not clutter the system. In combination with the small volume of the books themselves, this allows you to store a whole library on a computer or server, without the lack of physical memory.

More often than not, people learn about what Dejavu is like when unsuccessful attempts to open an unfamiliar format. And all because of the reluctance to read the description of the book, where there is a high probability of a link to a free program for reading. Including the program in the archive with each book is unprofitable because one of the merits of the format will disappear - a small file size. Compared with PDF, Dejavu wins by a factor of 3-5, yielding only to the colorfulness of the design and the possibilities for editing.

If the book is not divided into layers, the text search will not be possible, in this case only the table of contents will help in navigation. You can not edit this book, unlike the same PDF. But books are in fact needed primarily for reading, and you can create notes and notes in a separate file.

Now that you know what Dejavu is and how to open it, you can access a huge amount of literature distributed digitally, whether it's an old physics textbook or a hand-written poem by one of the classics.