Here is some matlab code for thresholding of continuos histograms.

Use the matlab help command for parameter information.

I do hope that the code is both readable and useful.

All files reside in the 
/usr/users2/joakim/matlab/public/chist2
directory.

Have fun and tell me how it worked.
/Joakim 



Usage examples:

For testing of many sigmas on a data-file.
>> chistplot('myfile.dat',1:4);

For testing many data-files, one sigma (here set to 2).
>> chistplotfiles('*.dat',2);

Automagic thresholding of an image using rule of thumb value for sigma
Note: It is rather slow, so don't try too large images.
>> mthresh(data);

Note: Suggested threshold is the largest peak in the second derivative,
which is not always the threshold we are interested in.

Tip: If you don't want to copy, just add the directory to your matlab path. 
If you want it permanently, put it in startup.m in your ~/matlab directory 
(which in your matlab path by deafault if you create it).


File listing:

High level functions:
 autothresh.m		automagic thresholding of an image
 chistplot.m		plots and thresholds a single data-file, 
			many sigmas allowed
 chistplotfiles.m	plots and thresholds many files

Mid level functions:
 chistplotone.m		plots and thresholds a continuos histogram
 chplot.m		plots a continus histogram
 d2chplot.m		plots a second derivative chist
 hplot.m		plots a histogram
 h_rot.m		rule of thumb value for sigma

Low level funcitons:
 chist.m		continuos version of the hist command
 d2chist.m		second derivative of chist
 x_interval.m		linear interval that surrounds the data

Low level, pure math:
 gauss.m		gaussian function
 dgauss.m		derivative of a gaussian (not used)
 d2gauss.m		second derivative of a gaussian

Help functions:
 dirren.m		directory help function
 linewidth.m		set linewith
 relaxx.m		show a little bit more of the plot
 relaxy.m
 scale_height.m		scale the height of the current plot


Last edit: 2000-07-28