For example, you can 1) introduce some threshold dividing "extracted" and "dimmed" subset of points by this fuzzy-set "degree of belonging" value; 2) "dim" each pixel by some factor proportional to this "degree of belonging" value, so the pixel value with degree of 0 was totally black, and those with degree of belonging 1 was totally untouched; 3) formulate some other criterion for representing the pixels with the "degree of belonging" more than 0 but less than 1.

See also:

http://en.wikipedia.org/wiki/Fuzzy_clustering#Fuzzy_c-means_clustering[^],

http://home.deib.polimi.it/matteucc/Clustering/tutorial_html/cmeans.html[^].

All required data is available from Matlab

`fcm`

; please learn the documentation: http://www.mathworks.com/help/fuzzy/fcm.html[^].