It is incredible that many of us not only use but also regularly practice the task of compressing files without understanding very well how this practice really works. The reality is that in a compression everything is transformed.
How does file compression work?
Basically compressing is removing redundant values from a file, or what is the same, removing what is repeated. Suppose a file is composed of “MMMMMM”, compressing it would be “6M”. Being more specific and looking for all these chains, compression programs can compress several megabytes in just KB of files that have not previously been compressed.
The difference between basic and redundant information is called entropy.
Methods used to compress:
1) Without loss:
– EXAMPLE FILES: ZIP, PNG, RAR, H264 and others
This method consists of summarizing the information by removing what is redundant, as we mentioned earlier. It is like saying the same thing but in another way, in a summarized or compressed way. The good thing about this compression is that it is reversible and the files do not lose any quality. When you unzip a file with this technique, it will have exactly the same composition as before compressing it or what is the same as having the original file.
2) With loss:
– EXAMPLE FILES: Mp3, Jpg, MPG
These files lose quality because the compression parameters are removed, although they are not strictly necessary, they remove integrity and quality from the file.
In an image file, brightness, thresholds, and quality are removed, while for example in audio files, spaces, volume, and frequencies not audible by the human ear are removed.
Creating compressed files today is an easy task, any image editor allows you to convert to Jpg for example. In lossless compression, it requires programs such as Winrar or Winzip, programs that have become common in the use of the Internet as they not only compress but also allow a large file to be divided into small parts to facilitate downloading.
