il image- 
and have 
(a) 
(b) 
(c) 
(d) 
(e) 
(f) 
», wl k 
(g) 
(h) 
(i) 
Figure 6. (a) Power spectrum of CASI frame 1(b) after filtering out the high spectral frequencies, as in spatial mode sampling, 
with a sharp cut-off. Only the lowest 16 spectral frequencies are non-zero of a possible 128. (b) Power spectrum of 
CASI frame 1(b) after filtering high spatial frequencies, as in spectral mode sampling,with a sharp cut-off. Only the 
lowest 16 spatial frequencies are non-zero of a possible 128. (c) Power spectrum of CASI frame 1(b) after filtering 
using the proposed cross method which combines the spatial and the spectral mode signals with a sharp cut-off. The 
cross is 16 wide both in the spectral and spatial directions, (d) Inverse Fast Fourier Transform (IFFT) of 6(a). (e) 
IFFT of 6(b). (f) IFFT of 6(c). (g) Difference between the original image 1(b) and the IFFT of the spatial mode 
sampled image 6(d). (h) Difference between the original image 1(b) and the IFFT of the spectral mode sampled 
image 6(e). (i) Difference between the original image 1(b) and the IFFT of the cross sampled image of 6(f). See 
figure 3 for the orientation and axes labels for all the power spectra images. 
576 
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