Compared to the existing method, the complexity of this method reduces. The multiplication operand is 2 ( N-1), the addition operand is 3N-2, and it suits the free length DCT. Thus the algorithm has the better application prospect in the image processing. 该方法与现有方法比较,复杂度降低,乘法运算量为(2N-1),加法运算量为3N-2,并且适合任意长度的DCT计算,因而在图像处理中具有较好的应用前景。