Difference between Lossy Compression and Lossless Compression

Data Compression refers to a technique that allows a large file to be reduced to a smaller-size. It also allows decompressing the compressed file back into its original form.

Lossy compression restores the large file to its original form with some level of loss in data which can be considered negligible, while lossless compression restores the compressed file to its original form without any loss of data.

Read through this article to find out more about Lossy and Lossless compression techniques and how they are different from each other.

What is Lossy Compression?

Lossy compression is a type of data encoding and compression that intentionally discards some data during the compression process. The lossy compression method filters and discards unnecessary and redundant data to lower the quantity compressed and then executed on a computer.

Digital multimedia such as audio, video, photos, and streaming data, benefit from lossy data compression. The sizes of these forms of data can be significantly decreased by utilizing lossy compression, ensuring convenient Internet distribution or offline consumption.

Lossy compression works by removing any excessive or redundant data from most multimedia files. A JPEG image, for example, can be shrunk by up to 80% of its original size without sacrificing visual quality. This can be accomplished by lowering the pixel count, brightness, and color density. Similarly, background audio sounds are removed from MP3 and MPEG without affecting the end-user experience much.

What is Lossless Compression?

Lossless compression entails compressing that data so that when the compression is reversed, the original dataset is fully recreated. This differs from "lossy" compression, in which some data is lost during the reversing process. Lossless audio compression is another name for lossless compression.

For various files such as executable programs and code modules, lossless compression means that all of the data in a compressed format must be entirely recreated when the compression is reversed. This service is provided by technologies such as zip file tools, resulting in fully reconstructed datasets after unzipping the files.

In contrast, some data loss after compression may be acceptable for music, images, or video. Because even though the quality of the media may be impacted, these formats will still be consumable and helpful despite minimal data loss.

Lossless compression is achieved using a set of highly advanced algorithms. These include modeling the data for compression to see how much storage space may be saved without impacting the dataset's reconstruction. Experts point out that various lossless compression algorithms operate in different ways. Lossless compression can be defined as a technology that reduces storage requirements while preserving data integrity. Some of these algorithms function on the idea of plausible versus improbable data building, in which algorithms anticipate or forecast how datasets might be put together to reconstruct a file.

A closer examination of lossless compression algorithms reveals that many operate on the notion of removing or coping with duplication. These techniques can make the files smaller while offering a shorthand that machines can use to reconstruct the data later using strategies like "bit string substitutions" and data conversion. There are various approaches around this, including using helpful pointers to provide consistent values for extra data bits.

Difference between Lossy Compression and Lossless Compression

The following table highlights the important differences between Lossy Compression and Lossless Compression.

Lossy Compression
Lossless Compression
Data Elimination
By using lossy compression, you can get rid of bytes that are regarded as unnoticeable.
Even unnoticeable bytes are retained with lossless compression.
After lossy compression, a file cannot be restored to its original form.
After lossless compression, a file can be restored to its original form.
Quality suffers as a result of lossy compression. It leads to some level of data loss.
No quality degradation happens in lossless compression.
Lossy compression reduces the size of a file to a large extent.
Lossless compression reduces the size but less as compared to lossy compression.
Algorithm used
Transform coding, Discrete Cosine Transform, Discrete Wavelet transform, fractal compression, etc.
Run length encoding, Lempel-Ziv-Welch, Huffman Coding, Arithmetic encoding, etc.
Lossy compression is used to compress audio, video and images.
Lossless compression is used to compress files containing text, program codes, and other such critical data.
The data holding capacity of the lossy compression approach is quite significant.
Lossless compression has low data holding capacity as compared to lossy compression.


From the above discussion, we can conclude that Lossy compression leads to some level of data loss and degradation in quality while decompressing a file back to its original form, however it can be used effectively to compress multimedia and image files in order to reduce their size to a great extent so that they can be easily transported over the Web. Moreover, data degradation is tolerable to a certain extent in multimedia files. Lossless compression, on the other hand, is used to compress files containing text, program codes, and other such forms of data where any data loss would make the files useless.