How file compression works

Unless you are new to the Internet, you have probably encountered compressed files before. People use either paid or free file compressor to reduce the number of bits and bytes in a file. The purpose of compressing a file is to make its size smaller and therefore easier to store and to share. After compressing a file, you can restore its contents perfectly with the help of the same program or specialized software. You do not need to use the exact same compressor to open or extract files as the one used to compress the file, but you will need to ensure that the program you use is able to read the file format you wish to extract.

The process of compressing a file


It might seem unusual for a program to be able to reduce the number of bits and bytes of files, only to add them back as if untouched later. However, the process is fairly simple to understand and straightforward. Starting with the idea that files are redundant, which they are because they repeat the same information multiple times, file compression software was designed to eliminate that redundant information, thus, reducing the overall size of the file considerably. A file compressor lists information once and returns to it each time it is repeated in the original file. The best way to explain this process is by taking a phrase and eliminating the words, punctuation, spaces and so on that repeat themselves. Expanding the file to its original size and content is done by reversing the process. Irrespective of the nature of the information, files always have redundant information and a free file compressor will help you eliminate it and reduce its size. Although it relies on a complex encryption process that uses varied algorithms, file compression is easy to understand.


Lossy vs. lossless compression


There are two types of file compression, each with its own advantages and disadvantages. One could choose either lossy or lossless compression, depending on your specific needs and the type of the file that needs to be compressed. Lossless compression will allow the user to recreate the original file perfectly. Just like its name suggests, you will be able to compress a file by breaking it and recreating it later without losing any information. Lossy compression will eliminate the information it catalogues as unnecessary to reduce the size of the file without giving the user the chance to recreate it later. It is used to reduce the size of images for instance. Lossless compression will not be able to reduce the size of an image by much, because pixels will differ slightly from each other even though they depict the same things, the blue of the sky for instance. Eliminating redundant information to recreate it later will not work with images. In this case, the bulky information will be completely eliminated and the quality of the image reduced. The resolution of the image will be compromised, because the lossy compressing program will pick the color value of a pixel and change the rest of the sky to the same color.