Image Processing Reference
In-Depth Information
5.3.4 Contrast Improvement Using the Fuzzy Expected Value
The use of the fuzzy expected value (FEV) in image enhancement was
proposed by Schneider and Craig [14] where the image quality is improved
in terms of the distance between the grey levels and the FEV. The FEV by
Friedman et al. [9] replaces the mean and median value with a more repre-
sentative value or 'typical value' when treating with fuzzy sets. This value
would indicate a typical grade of membership of a fuzzy set.
Example 5.1
Two examples are shown in Figures 5.2 and 5.3 to show the contrast
enhancement of blood vessels using four fuzzy methods for image
enhancement on low-contrast blood vessel images.
As it is difficult to say which method will perform the best, researches are
carried out to improve the quality of contrast of the resultant images. Fuzzy
methods do provide better results, but in some cases, they fail to provide
better results. Intuitionistic fuzzy (IF) set and Type II fuzzy set theoretic
techniques are used bearing in mind that as these sets consider more uncer-
tainties, better results may be obtained. So, when fuzzy methods in some
cases fail to provide better results, advanced fuzzy techniques may be used.
(a)
(b)
(c)
(d)
(e)
FIGURE 5.2
(a) Blood vessel (BV1) image, (b) enhancement using the FEV, (c) enhancement using the INT
operator, (d) enhancement using the NINT operator and (e) enhancement using histogram
hyperbolization.
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