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Lossy Compression


Lossy compression is a data compression method. It produces a close match of the data after decompression. The lossy compression method eliminates some amount of data that is not noticeable. this technique does not allow a file to restore in its original form but significantly reduces the size. It is beneficial if the quality of the data is not your priority. It slightly degrades the quality of the file or data but is convenient when one wants to send or store the data. It is used to store audio signals, images and videos. The data holding capacity of channel is more than the lossless method. 

The application of the lossy compression are the following:
JPEG, GUI, MP3, MP4, OGG, H-264, MKV, etc.

Lossy Compression Technique
  1. Transform Coding: This method transforms the pixels which are correlated in a representation into disassociated pixels. The new size is usually less than the original size and reduces the redundancy of the representation.
  1. Discrete Cosine Transform (DCT): This is the most vastly used image compression technique. JPEG process centre around DCT. DCT process divides the image into distinct parts of frequencies. In the quantization step, where compression basically occurs least important frequency are rejected. And the critical frequencies are retained so that the image can be obtained in the decompression process. The reconstructed image could contain some distortion.
  2. Discrete Wavelet Transform (DWT): It provides a location of time and frequencies simultaneously and can be utilised in decomposing a signal into component wavelets.

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