最大似然（ML）准则和最大后验概率（MAP）准则，是学习PCA特征提取的很好的学习资料，表示出两帧图像间各个像素点的相对情况。- Maximum Likelihood (ML) criteria and maximum a posteriori (MAP) criterion, Is a good learning materials to learn PCA feature extraction, Between two images showing the relative circumstances of each pixel.