Method and apparatus for performing fast discrete cosine transforms and fast inverse discrete cosine transforms using look-up tables
CA 2172486 A1 · Owner: Vivo Software, Inc. · Inventors: Ericsson, Staffan; Girod, Bernd
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method is provided for performing a, fast Discrete Cosine Transform (DCT) and a fast Inverse Discrete Cosine Transform (IDCT) in a software implementation. The method provided exploits symmetries found in both the DCT and IDCT. As a result of the symmetries found in the DCT and IDCT, both transforms may be performed using a combination of look-up tables and butterfly operations, thus employing only a small number of additions and subtractions and no multiplications. Furthermore, there is provided an aspect of the present invention which exploits the excess precision available in current central processing units (CPUs) relative to the precision required by the DCT and IDCT calculations.
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed September 23, 1994. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended September 23, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 23, 2016.
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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.