Image Processing Reference

In-Depth Information

Fig. 4.8
Plots of PSNR of the fused images against the timing requirements for the urban and the

moffett
2
data for the bilateral filtering-based fusion technique. The resultant image from the fusion

of the entire dataset is used as a reference in each case for the evaluation of the PSNR (© ACM

2010, Ref: [87])

process. Therefore, the entropy-based subset selection scheme proves to be highly

effective for complex and computationally extensive techniques of fusion. The total

computation
W
, taken for the pixel-level fusion procedure as a function of threshold

κ

, is of the form-

W

(κ)
=
γ B(κ)
+

c
E

(4.12)

where

, and

c
E
is the amount of computation for the evaluation of conditional entropies of the

image bands for the band selection procedure. This second term is a constant for a

given dataset. The

B(κ)

represents the number of bands selected for a given threshold

κ

factor is a proportionality factor to account for computational

requirements of a given fusion technique. If the time required for the computation

of the conditional entropy is negligible as compared to the timing requirements of

actual fusion, we can approximate Eq. (
4.12
)as,
W

γ

which indicates

that the order of computation is linear with respect to the number of bands selected.

It should be noted that as

(κ)
≈
γ B(κ)

decreases leading to a lesser amount

of computation, however this does not affect the linear nature of the computational

complexity.

For a qualitative analysis of the band selection scheme for the computational

requirements, we provide the plot of PSNR of fused images against the total time

taken by varying the threshold parameter

κ

increases,

B(κ)

. Figure
4.8
depicts the plots for the urban

and the moffett
2
datasets for fusion using the bilateral filtering-based technique.

A monotonically increasing nature of these plots indicate the improvement in the

quality of the fusion result at the expense of computational requirements when more

bands are fused. The reason that the computational requirements are nearly double

κ