Discrete Cosine Transform (DCT)
Discrete Cosine Transform (DCT)
Discrete Cosine Transform (DCT)
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4 πu<br />
cos<br />
The multiplication by Cu 16 seems not so<br />
efficient. However, bear in mind that the last<br />
operation before the I<strong>DCT</strong> is the<br />
“Quantization”. That means every value is to<br />
be multiplied with a certain constant<br />
(1/Quantization factor) depending on its<br />
position in <strong>DCT</strong> matrix. So we can merge the<br />
4 πu<br />
multiplications by cos<br />
C and the multiplication<br />
u 16<br />
by Quantizer dependent constant together.<br />
As a result, the Quantization and <strong>DCT</strong>-DFT<br />
transform is performed in one step.<br />
20
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