JPEG: Quantization (Weighting of the Contents)

The result of the DCT is a set of values also describing the image contents. In contrast to the original format they do not affect the image quality in the same manner. The reason is the subjectively different perception of details.

With the help of quantization more relevant values are described with a higher accuracy. Values influencing the subjective perception to a smaller extend will be devalued and represented with lower range of values.

Quantization is not reversible and substantially affects the image quality.

The quantization is processed with special tables which will be stored within the corresponding JPEG file. They are essential for decoding.

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