How does data compression work from a technical standpoint? Well, the actual algorithms that decide what data gets thrown out (in lossy methods) and how to best store redundant data (in lossless compression) are extremely complicated.
No: Converting one lossy format to another lossy format.No: Converting lossy files to lossless files (lossy formats throw out data it’s impossible to recover that data).Yes: Converting one lossless format to another lossless format is fine.Yes: Converting lossless files to lossy files.
How to reduce a file size with rar zip#
Compressing a file into a ZIP may reduce its size, but it is impossible to continue compressing the file further and reduce the size to nothing.Īlso, it’s important to understand the relationship between the two groups of data compression: It’s important to note that compression is not infinite. Lossless formats for video are rare, as the source files would take up massive amounts of space. Decompressing the file (unzipping) produces an executable program that would otherwise be useless with lossy.Ĭommon lossless formats include PNG for images, FLAC for audio, and ZIP. With lossless, it is possible to perfectly reconstruct the original file.įor example, the most common lossless compression format (ZIP) is often used for program files in Windows, as it preserves all the original information. Instead, this format works by removing redundancies within data to reduce the overall file size. Lossless compression reduces file size without removing any bits of information. Also, lossy compression does not work well with files where all of the data is crucial (for example, compressing a spreadsheet would yield unusable results). The downside? The more heavily a file is compressed with lossy compression, the more noticeable the reduction in quality becomes. Since the average human ear would not notice this difference, the result is a smaller file with minimal user impact. Instead, MP3 lossy compression removes sounds that humans can’t hear.
This type of compression is most commonly used on image, video, and audio files, where a perfect representation of the source media is not required.įor example, an MP3 audio file doesn’t contain all the audio information from the original recording. Lossy compression reduces file size by removing unnecessary bits of information. To better understand data compression in general, it’s easiest to split the process down into two main groups: lossy compression and lossless compression. Today, there are many different types of algorithms and implementations that allow the everyday user to compress files, but some are more suited for certain applications. Morse code, invented in 1838, is the earliest instance of data compression in that the most common letters in the English language such as “e” and “t” are given shorter Morse codes.Ĭommon data compression algorithms include: LZW compression was the first widely used data compression method implemented on computers and it is still used today (in various iterations): a large English text file can typically be compressed to about half its original size with LZW. Mathematicians around the world addressed the problem for years, but it wasn’t until the Lempel-Ziv-Welch (LZW) universal lossless compression algorithms came on the scene in the mid-1980s that real benefits were realized. A Brief History of Data CompressionĪs the Internet emerged in the 1970s, the relationship between file size and transfer speed became much more apparent. A fundamental component of data compression is that the original file can be transferred or stored, recreated, and then used later (with a process called decompression). Data compression is a process in which the size of a file is reduced by re-encoding the file data to use fewer bits of storage than the original file.
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