说明：  对任意大小的灰度图像进行zig-zag变换和反变化，或者是对DCT之后的图像进行zig-zag变换，确定其中频信息。
(Any size of gray-scale images in zig-zag transform and anti-change, or is the DCT of the image after the zig-zag transform, to determine which frequency information.)