N. I. Cho and S. U. Lee (1991) proposed a fast algorithm for 2-D N*N DCT, where N=2/sup m/. It requires only half the number of multiplications of the conventional row-column approach. However, the signal flow graph for the postaddition stage seems very complicated and the order of the output index is seemingly irregular, because the postaddition stage was not based on the mathematical expressions. Consequently, derivation of the signal flow graph becomes complicated as the transform size increases. Systematic expressions for the postaddition stage of the algorithm that enable any N*N DCT to be implemented in a straightforward manner are provided here. The results show that the signal flow graph from input to output has a recursive structure in which the structure for smaller N reappears for larger N. However, the number of additions increases in the new signal flow graph at the expense of improving the regularity in the structure.
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机译：N.I.Cho和S.U.Lee（1991）提出了一种针对二维N * N DCT的快速算法，其中N = 2 / sup m /。它仅需要传统行列方法的乘法次数的一半。但是，由于加法后阶段不是基于数学表达式，因此加法后阶段的信号流图看起来非常复杂，输出索引的顺序似乎不规则。因此，随着变换尺寸的增加，信号流图的推导变得复杂。这里提供了用于算法的加法后阶段的系统表达式，该表达式使任何N * N DCT都能以简单的方式实现。结果表明，从输入到输出的信号流图具有递归结构，其中较小的N的结构又出现在较大的N上。但是，新信号流图中的相加数增加了，但代价是提高了信号流图的规则性。结构体。
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