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Difference between Lossless and Lossy data compression.

Before learning the difference between lossless and lossy data compression lets, first understand the data compression, lossless data compression, and lossy data compression.

What is Data Compression

Data Compression is also referred to as bit-rate reduction or source coding. This technique is used to reduce the size of large files.

The advantage of data compression is that it helps us save our disk space and time in the data transmission.

There are mainly two types of data compression techniques –

1. Lossless Data Compression
2. Lossy Data Compression

What is Lossless data compression

Lossless data compression is used to compress the files without losing an original file’s quality and data. Simply, we can say that in lossless data compression, file size is reduced, but the quality of data remains the same.

The main advantage of lossless data compression is that we can restore the original data in its original form after the decompression.

Lossless data compression mainly used in the sensitive documents, confidential information, and PNG, RAW, GIF, BMP file formats.

Some most important Lossless data compression techniques are –

1. Run Length Encoding (RLE)
2. Lempel Ziv – Welch (LZW)
3. Huffman Coding
4. Arithmetic Coding

What is Lossy data compression

Lossy data compression is used to compress larger files into smaller files. In this compression technique, some specific amount of data and quality are removed (loss) from the original file. It takes less memory space from the original file due to the loss of original data and quality. This technique is generally useful for us when the quality of data is not our first priority.

Note: The human eye does not measure the loss of data.

Lossy data compression is most widely used in JPEG images, MPEG video, and MP3 audio formats.

Some important Lossy data compression techniques are –

1. Transform coding
2. Discrete Cosine Transform (DCT)
3. Discrete Wavelet Transform (DWT)

Difference between lossless and lossy data compression

As we know, both lossless and lossy data compression techniques are used to compress data form its original size. The main difference between lossless and lossy data compression is that we can restore the lossless data in its original form after the decompression, but lossy data can’t be restored to its original form after the decompression.

The below table shows the difference between lossless and lossy data compression –

S.No	Lossless data compression	Lossy data compression
1.	In Lossless data compression, there is no loss of any data and quality.	In Lossy data compression, there is a loss of quality and data, which is not measurable.
2.	In lossless, the file is restored in its original form.	In Lossy, the file does not restore in its original form.
3.	Lossless data compression algorithms are Run Length Encoding, Huffman encoding, Shannon fano encoding, Arithmetic encoding, Lempel Ziv Welch encoding, etc.	Lossy data compression algorithms are: Transform coding, Discrete Cosine Transform, Discrete Wavelet Transform, fractal compression, etc.
4.	Lossless compression is mainly used to compress text-sound and images.	Lossy compression is mainly used to compress audio, video, and images.
5.	As compare to lossy data compression, lossless data compression holds more data.	As compare to lossless data compression, lossy data compression holds less data.
6.	File quality is high in the lossless data compression.	File quality is low in the lossy data compression.
7.	Lossless data compression mainly supports RAW, BMP, PNG, WAV, FLAC, and ALAC file types.	Lossy data compression mainly supports JPEG, GIF, MP3, MP4, MKV, and OGG file types.

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