tomwalters@0: % method of class @frame
tomwalters@0: % 
tomwalters@0: %   INPUT VALUES:
tomwalters@0: %  
tomwalters@0: %   RETURN VALUE:
tomwalters@0: %
tomwalters@0: % 
tomwalters@0: % (c) 2003, University of Cambridge, Medical Research Council 
tomwalters@0: % Stefan Bleeck (stefan@bleeck.de)
tomwalters@0: % http://www.mrc-cbu.cam.ac.uk/cnbh/aimmanual
tomwalters@0: % $Date: 2003/03/13 14:48:22 $
tomwalters@0: % $Revision: 1.6 $
tomwalters@0: 
tomwalters@0: function nap=logcompress(nap,options)
tomwalters@0: 
tomwalters@0: %if nargin <2
tomwalters@0: %    options.dynamic_range=50;
tomwalters@0: %end
tomwalters@0: 
tomwalters@0: nap=halfwayrectify(nap);
tomwalters@0: vals=getvalues(nap);
tomwalters@0: 
tomwalters@0: %gtfb output values are: 0< gt_vals <1
tomwalters@0: %therefore we will scale for 16bit values
tomwalters@0: %operationally only 15 bits are used as we
tomwalters@0: %half wave rectify
tomwalters@0: vals=vals.*2.^15;
tomwalters@0: 
tomwalters@0: %avoid log problems by making everything > 1
tomwalters@0: vals(find(vals<1))=1;
tomwalters@0: vals=20.*log10(vals);
tomwalters@0: 
tomwalters@0: 
tomwalters@0: nap=setvalues(nap,vals);
tomwalters@0: