JPEG
Quantization of the DCT coefficient based upon human vision.
For this quantization, the DCT coefficient is multiplied by the quantization coefficient and the frequency value; this results in an increase in the number of "0"s (based on characteristics of human vision), and therefore increases the compression ratio.For example, an 8 x 8 DCT coefficient data block (16 bits) is multiplied by an 8 x 8 quantized coefficient (16 bits), and through the final reduction, is reduced to 16 bits. The quantized coefficient is derived from the physical characterstics of human vision.
There is a great deal of memory saved in DCT with no loss in picture quality.