Steps
1. The first step is to obtain a set S with M face images. In our example M = 25 as
shown at the beginning of the tutorial. Each image is transformed into a vector of size
N and placed into the set.
M
S , ......... , , ,
321
2. After you have obtained your set, you will obtain the mean image Ψ
3. Then you will find the difference Φ between the input image and the mean image
4. Next we seek a set of M orthonormal vectors, u
n
, which best describes the
distribution of the data. The k
th
vector, u
k
, is chosen such that
求特征值:
otherwise
if
0
1 kl
uu
lkk
T
l
Note: u
k
and λ
k
are the eigenvectors and eigenvalues of the covariance matrix C
5. We obtain the covariance matrix C in the following manner
, ....... , , ,
321 n
A
. The matrix C, however, is N
2
by N
2
, and determining the N
2
eigenvectors and eigenvalues is an intractable task for
typical image sizes. We need a computationally feasible method to find these
eigenvectors.
4
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