Lossy vs lossless compression



When it comes to storing data, memory space can be an issue. Naturally, you want to optimise the space you have — and that means reducing the size of files as much as possible.

This is where compression comes in. That is, techniques to reduce the size of data without losing the information. There are two categories of compression to know about: lossy and lossless.

But what are the differences, and which is better? Let’s take a closer look at lossy vs lossless compression.


Lossy compression

Lossy compression is where the compression process reduces file size by deleting any unnecessary or extraneous data — that which won’t prevent the computer from representing the content in question.

In other words, it reduces file size by removing data without removing information. It’s also known as irreversible compression because it involves permanently removing the excess data — files are not restorable to their original state after lossy compression.

Lossy compression is most commonly used for storing images but is also used for other multimedia data like audio and video. In images, lossy compression algorithms remove the details that the eye cannot distinguish. Extra pixels and colours, for instance.

A well-known example of a lossy compression format is JPEG, used for digital images.


Lossless compression

Lossless compression is the other side of the lossy vs lossless compression coin. Where lossy compression works by removing extraneous data, lossless compression encodes digital files without losing the extra details. Lossless compression is also known as reversible compression because it allows files to be restored.

In other words, lossless compression does not sacrifice the quality of the image or files compressed. But as a pay-off, it doesn’t reduce the size of the files in question as much.

Lossless compression can be used on images but is more commonly used on text and data files.


Lossy vs lossless: pros and cons

Lossy
  • Pros

In the lossy vs lossless compression question, a pro of the lossy method is that it offers a greater reduction in file size.

In turn, this means that lossy compression makes for more data holding capacity. Smaller file sizes also make for faster loading and better performance.

  • Cons

The cons of lossy compression are twofold. First, lossy compression sacrifices the quality of the data compressed.

Second, the removal of the unneeded data is irreversible. So, with lossy compression, you cannot restore the files to their original quality.

Lossless
  • Pros

The main pro of lossless compression over lossy is that it doesn’t sacrifice quality to reduce file size. All the data remains.

Additionally, the compression can be reversed, allowing files to be restored to their original state.

  • Cons

However, in the lossy vs lossless questions, it’s important to note that lossless compression cannot reduce the size of files as much as lossy can.


Lossy vs Lossless compression

To recap: lossy compression is a compression strategy that involves removing unneeded detail. Lossless compression does not result in losing this data, but at the cost of a smaller reduction in file size.

Both lossy and lossless compression have their benefits and their drawbacks. And both have their uses in the world of data storage and management.


Useful links

Is data a liability?

ELI5: what is image classification in deep learning?

Everything wrong with manual data entry


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