If you have downloaded some files or programs over the internet, then you’ve probably come across ZIP files. The system of compressing files is a handy invention, particularly for users of the internet, because it makes it possible to reduce the general number of bytes and bits in a file, so it can be transferred faster over slow internet connections, or consume less disk space. File compression has become an important part of the web.
So, what is File Compression?
Data compression or file compression is a process of reducing the size of a file, without losing its original data. Doing so makes it possible for the file to consume less space on any storage device; it allows transfer over the internet and other means much easier.
How File Compression Works?
At first, it may seem quite mysterious. How can the number of bytes and bits be reduced and still get back those same bytes and bites later? As it turns out, the process makes use of a straightforward idea. A number of computer files are redundant – meaning they contain the same kind of information listed repeatedly. Programs that compress files do so by getting rid of such redundancy. Instead of repeatedly listing information, a compression program lists that information once and goes back to it when it appears in the program.
Types of Compression
It is important to know that compression is finite. As you compress a file to reduce the size, you cannot continue compressing that file and reduce the size to nothing. Generally speaking, there are two types of file compression – lossy and lossless.
Lossy File Compression
This reduces the size of a file by getting rid of bits of information that are not necessary. It is common in video, audio, and image formats, where a representation of the source media is not important. Most formats for these media files make use of lossy compression – JPEG and MP3 are the most common examples.
JPEG files remove parts of the image that are not important. For example, a picture that contains a blue sky can be compressed to change the pixels of the sky to some shades of blue, rather than making use of various shades. Similarly, an MP3 does not have all the audio information from an original recording. Rather, it deletes some sounds that cannot be heard by humans. It is impossible to notice them missing anyway, so throwing them out to give a lower size of file has no drawbacks.
However, the more a file gets compressed, the more you’ll notice the reduction in quality. You have probably come across such files over the internet. It is suitable to make use of lossy compression when a file has more information than needed. This kind of compression is good for most kinds of media. Due to this, most companies such as Netflix and Spotify makes use of them regularly.
Lossless File Compression
This is a perfect way of reducing the size of a file so that the original file can be perfectly reconstructed. As opposed to lossy compression, it doesn’t remove any information. Rather, it removes redundancy. For instance, the information contained in the popular quote ‘Ask not what your country will do for you, ask what you can do for your country’ by a past president of the US is made up of 17 words, 61 letters, 16 spaces, 1 period, and 1 comma. If every letter, punctuation or space consumes one memory unit, that will take up 79 units in total.
Lossless compression seeks to remove such redundancy. It can be noticed that some words are repeated – words such as ask, country, can, for, do, you, what, all appear two times, this implies that almost half of the sentence is redundant. Everything needed for the entire quote can be gotten from only nine words. To make the second part of the quote, the program just refers to a first part and fills in the punctuation and spaces.
WinZip for windows can be used to create a ZIP file. It makes use of lossless kind of compression. This compression is an efficient way of storing a program and still getting the original information after unzipping it. It is not advisable to make use of lossy compression for executables, as it will damage or make the unzipped version unstable. You can open a ZIP file by installing WinZip for Windows. After installation, double click on the attachment or the Explorer window. You can also open the WinZip App.
