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Algorithm Alley

By Tim Kientzle, March 01, 1999

The Discrete Cosine Transform (DCT) is a crucial part of modern image and sound compression. Tim discusses several fast algorithms for computing the 8-point DCT and IDCT.
Mar99: Algorithm Alley

Implementing Fast DCTs

By Tim Kientzle

Dr. Dobb's Journal March 1999 

C =  A  + B * ( sin(3<img src="http://twimgs.com/ddj/ddj/images/ddj9903m/pi14.gif" width="7" height="7">/8) / cos(3<img src="http://twimgs.com/ddj/ddj/images/ddj9903m/pi14.gif" width="7" height="7">/8) )
D = -A * (sin(3<img src="http://twimgs.com/ddj/ddj/images/ddj9903m/pi14.gif" width="7" height="7">/8)/cos(3<img src="http://twimgs.com/ddj/ddj/images/ddj9903m/pi14.gif" width="7" height="7">/8)) + B
C *= cos(3<img src="http://twimgs.com/ddj/ddj/images/ddj9903m/pi14.gif" width="7" height="7">/8)
D *= cos(3<img src="http://twimgs.com/ddj/ddj/images/ddj9903m/pi14.gif" width="7" height="7">/8)

Example 2: Rewriting a rotation with only two internal multiplications.

Copyright © 1999, Dr. Dobb's Journal


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