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Lossless Compression

1. What is lossless Compression?

Lossless compression is a data compression process that reduces the size of the file without compromising the quality of the image. No information is lost while using lossless compression. Since no data is removed from the file, it can not be compressed to the same degree as lossy compression.

2. Algorithms used in Lossless Compression

  • RLW
  • LZW
  • Arithmetic encoding
  • Huffman encoding
  • Shannon Fano coding
A closer look at lossless compression algorithms show that many of them work through the principle of eliminating or handling redundancy. Using strategies like bit string replacements and data conversion, these algorithms can make files smaller while providing a kind of shorthand that machines can use to reconstitute the data at a later time. Again, there are many ways to do this, including helpful pointers that can provide consistent values for redundant bits of data.

3. When should you use lossless compression?

Lossless compression reduces file size but retains redundant information after compression. For example, LZ77 is a type of lossless compression.
Lossless compression is good if there will be new analysis on the data. This is because it doesn’t alter any of the original values. This means that it’s good for discrete data or any raster image that is already lossy compressed.

4. Where can lossless compression be used

Text or program

Text compression is an important area for lossless compression. It is very important that the reconstruction is identical to the original text, as very small differences can result in statements with very different meanings.
Data obtained from satellites often are processed later to obtain different numerical indicators of vegetation, deforestation, and so on. If the reconstructed data are not identical to the original data, processing may result in “enhancement” of the differences. It may not be possible to go back and obtain the same data over again. Therefore, it is not advisable to allow for any differences to appear in the compression process


Lossless compression means that you reduce the size of an image without any quality loss. Usually this is achieved by removing unnecessary metadata from JPEG and PNG files. We say usually, because with some other compression algorithms, like Imagify, other compression opportunities are leveraged without sacrificing the image’s quality. In theory, there are some image formats that are considered to be “lossless” such as GIF, PNG and BMP. However, depending on how they are optimized for the web, these formats may see a slight loss in quality (that your eyes won’t be able to pick up). The big benefit of lossless compression is that it allows you to retain the quality of your images while reducing their file size.


Bandwidth is consumed every time the database loads a file. This uses 100 mb of bandwidth on your database if you get 100 page views with 1024 kb of photos on the site.
A very small group of users would be willing to exhaust 100 mb of their data to consume the content of your site. It becomes more dreaded if you happen to have high traffic on your site, as it will definitely lower the performance of your site. It in turn means lower conversion rate

5. Advantages and Disadvantages of Lossless compression


  • Useful for large files
  • Exact data is restored after re-compression
  • High-quality data


  • Compression ratio is low
  • Transfer time is high
  • Decoding is difficult

6. Conclusion

Lossless compression is ideal for archiving, compliance and long-term preservation of documents. without affecting the quality of your files. With lossless compression file sizes are reduced significantly while maintaining key information to meet compliance regulations.

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