JPEG压缩算法的核心是“视觉保真”原理，利用人类视觉系统特征进行处理，以达到最大图像数据压缩效果，实际上就是去除那些人眼不易觉察的信息。图像的空间频率对人的视觉至关重要，采用离散余弦变换可将图像分解成一组波，每个波有一个不同的空间频率，这样可以去除人类眼睛觉察不到的信息，而且还可使系统只保留重要的信息。-JPEG compression algorithm is the core of " visual fidelity"　principle, the use of the characteristics of human visual system to deal with in order to achieve the greatest effect of the image data compression is actually not easy to remove the eyes of those who perceived the information. Image spatial frequency is essential to human vision, the use of discrete cosine transform image can be broken down into a set of waves, each wave has a different spatial frequency, so aware of the human eye can not see the removal of information, but also to make system, only the important information.