dct变换与dct逆变换，程序可以直接运行，代码中有详细注释，容易理解。-dct dct transform and inverse transform, the program can run the code in detail in notes, easy to understand.

本代码演示了普通DCT,快速DCT,快速IDCT算法的实现-This code demonstrates common DCT, fast DCT, fast IDCT algorithm implementation,,