sig=antitilt(sig,tilttime)

% method of class @signal
% usage: sigresult=tilt(sig,tilttime)
% puts the signal upright!
% in the auditory image model, all activities become
% smaller with the distance
% usually with a decrease of 100% in 40 ms
% if you call tilt with tilt(sig,0.04), this tilt is reversed
%
%   INPUT VALUES:
%       sig:  original @signal
%       tilttime: time in seconds that the old signal is assumed to go from 100% to 0
%       [default: 0.04]
%
%   RETURN VALUE:
%       sigresult:  @signal
%
% (c) 2003, University of Cambridge, Medical Research Council 
% Stefan Bleeck ([e-mail])
% http://www.mrc-cbu.cam.ac.uk/cnbh/aimmanual
% $Date: 2003/01/17 16:57:42 $
% $Revision: 1.3 $

function sig=antitilt(sig,tilttime)

if nargin<2
    tilttime=0.04;
end

vals=sig.werte;

if getminimumtime(sig)>0
    return
end
durationtotilt=abs(getminimumtime(sig));
tiltnr=time2bin(sig,0); % so viele Punkte werden getiltet
dt=tilttime-durationtotilt; % brige Zeit, die links aus dem Bild rausgeht
dnull=dt/tilttime;
ti=linspace(dnull,1,tiltnr)';
vals(1:tiltnr)=vals(1:tiltnr)./ti;
% figure
% subplot(2,1,1)
% plot(sig);
sig.werte=vals;
% subplot(2,1,2)
% plot(sig);