JPEG dct快速算法，实现8X8到4X4，以及8X8到2X2等DCT变换，快速实现降采样。,JPEG dct fast algorithm 8X8 to 4X4, and 8X8 to 2X2, such as DCT transform, rapid down-sampling.

在VC6.0中进行位图的打开，下采样和保存-In VC6.0 to open the bitmap, down-sampling and preservation