Image compression is nowadays an indispensable part of our daily lives. It falls into two groups, lossy compression and lossless compression. One of the most useful image compression algorithms is JPEG algorithm, which belongs to the lossy compression group. For efficient compression, JPEG algorithm uses the discrete cosine transformation, which transforms the image into a frequency domain, that we can more easily remove insignificant parts of the image. Despite the fact that the data is lost during the JPEG algorithm, we can retrieve this data in the reverse order of compression and reconstruct the approximation of original image. Reconstructed image is not exactly the same as the original, but it is so similar that we usually do not notice the difference with our human eye.
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