（1）试利用函数dct2，对该图像进行压缩。压缩时可尝试对DCT 变换后的系数采用不同取舍方法，比较其压缩性能。（函数dct2在matlab本身是有的，可以help dct2看看）

（2）结合课本例8.7.2 的量化方法，对每一个经DCT变换后的8×8 矩阵量化（Huffman编码部分可省略），从而实现图像压缩。在一定压缩比的情况下，和⑴给出的图像质量相比较。

（3）用所给的子子程序fast_LOT.m 实现对该图像的变换与压缩，并和（1）得出的图像质量相比较-(1) Test using function dct2, the image is compressed. The compression can try to adopt different choices, the DCT transform coefficients after comparing its compression performance. (Function dct2 the matlab itself is some help dct2 see) (2) combined with the textbook cases 8.7.2 of quantitative methods, 88 each DCT transform matrix quantization (Huffman encoding part can be omitted) thereby achieving the image compression. In the case of a certain compression ratio, and the image quality given by the ⑴ compared. (3) with the given sub-subroutine fast_LOT.m transform and compress the image, and (1) gives the image quality compared