Image Processing Reference
In-Depth Information
that for a larger window, such asa5×5,theimage may be restored to within one
pixel of the original.
The error of 14 pixels could have been calculated by comparing the restored
image
opt ( I n ) to the ideal image I o and counting the pixels that differ. However, this
and other measures may be obtained from the table of observations, which is the
topic of the next chapter.
ψ
2.8 Summary
This chapter has shown an example of a simple restoration process using an opti-
mum filter. It has defined what is meant by constraint and error criterion. It has
shown how a table of observations may be constructed from noisy and ideal test im-
ages, and it has shown how the logical function defining the optimum filter may be
determined from the table of observations. This table may also be used to determine
various other errors and to compare different types of filters, the subject of the next
chapter.
References
1
D. R. K. Brownrigg, “The weighted median filter,” Commun. ACM , 27 , 807-
818 (1984).
2
M. Ghanbari, Video Coding: An Introduction to Standard Codecs , IEE London
(1999).
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