USAGE: fuzzythresh [-r radius] [-g graph] infile outfile
USAGE: fuzzythresh [-help]

-r ..... radius ......... radius for spatial correlation; float;
......................... radius>=0; the default=0 signifies to
......................... ignore spatial correlation
-g ..... graph .......... graph specifies whether to generate a
......................... histogram graph image displaying the
......................... location and value of the threshold;
......................... choices are: view or save;
......................... default is no graph

PURPOSE: To automatically thresholds an image to binary (b/w) format using the fuzzy c-means technique.

DESCRIPTION: FUZZYTHRESH automatically thresholds an image to binary (b/w) format. It assume the histogram is bimodal, i.e. is the composite of two bell-shaped distributions representing the foreground and background classes. The fuzzy c-means appoach iteratively thresholds the image, computes a weighted mean for the foreground (above threshold data) and background (at and below threshold value), computes a new threshold equal to the average of these two means and repeats until there is no change in threshold between successive iterations. The weighting factors are the normalized inverse square difference between each pixel in the foreground or background data sets and the corresponding mean. However, to allow for spatial correlation of the graylevels among neighboring pixels, a Gaussian filtered version of the weighting factors may be used. This script is similar to the isodatathresh script, except uses a weighted mean calculation.

ARGUMENTS:

-r radius ... RADIUS is the radius of a Gaussian (blur) filter to apply to the weighting factors for the mean calculation. This permits spatial correlation of the graylevels among neighboring pixels and is useful to remove noise from the result. The radius value should be set to the size of the features in the image. Values are floats greater than zero. The default=0 signifies to ignore spatial correlation.

-g graph ... GRAPH specifies whether to generate a graph (image) of the histogram, displaying the location and value of the threshold. The choices are: view, save and none. If graph=view is selected, the graph will be created and displayed automatically, but not saved. If graph=save is selected, then the graph will be created and saved to a file using the infile name, with "_histog_fuzzy.gif" appended, but the graph will not be displayed automatically. If -g option is not specified, then no graph will be created.

NOTE: It is highly recommended that the output not be specified as a JPG image as that will cause compression and potentially a non-binary (i.e. a graylevel) result. GIF is the recommended output format.

REFERENCES: see the following:
http://www.iiitmk.ac.in/wiki/images/d/d2/Fuzzy_CMeans.pdf
http://www.quantlet.com/mdstat/scripts/xag/html/xaghtmlframe149.html
http://home.dei.polimi.it/matteucc/Clustering/tutorial_html/cmeans.html

CAVEAT: No guarantee that this script will work on all platforms, nor that trapping of inconsistent parameters is complete and foolproof. Use At Your Own Risk.