说明：  JSteg隐写技术matlab实现代码--基本思想：用秘密信息比特直接替换JPEG图像中量化后DCT系数的最低比特位，但若量化后DCT系数为0或者1，则不进行处理。（DCT系数的LSB嵌入）
(JSteg steganography matlab code- the basic idea: direct replacement with the secret information bits JPEG image quantized DCT coefficients in the least significant bit, but if the quantized DCT coefficient is 0 or 1, no processing. (DCT coefficients LSB embedding))