
56 ◾ Jingang Zhong and Jiawen Weng
by the FT are well eliminated in the AWFT. Compared with Figure2.18,
Figure2.26 shows better spatial frequency resolution using AWFT, with
the contour line concentrating most of the energy and matching the true
instantaneous frequency curve well.
e WT is another spatial frequency analysis method for signal
analysis. Here, the Gabor wavelet transform (GWT) method [11,12]
0 100 200 300 400
0
5
10
15
20
25
30
35
40
Position/Pixel
Scale Factor a
FIGURE 2.21 e scale factor of the Gaussian window.
(a)
FIGURE 2.22 e local fringe patterns centered at the (a) 70th pixel and (b)
300th pixel selected by Gaussian w