function gfcheckfilter2(f0,theta,gamma,eta,n,pt,pf)%GFCHECKFILTER2 Check 2-d filter parameters.%%   GFCHECKFILTER2(F0,THETA,GAMMA,ETA,N,PT,PF)  Checks the%   constraints of the discrete Gabor filter for given parameters%   and prints out warning or error messages.%%     F0    - Central frequency%     THETA - Orientation%     GAMMA - Width parallel to wave%     ETA   - Orthogonal width%     N     - Size of the filter%     PT    - Spatial domain percent factor%     PF   - Frequency domain Percent factor, (major and minor axes)%%   Examples%%     gfcheckfilter2(1/64, pi/2, 1, 1, 64, 0.998, 0.998);%     gfcheckfilter2(1/64, pi/2, 1, 1, 64, 0.998, [0.998 0.95]);%%   See also GFCREATEFILTER2, GFCREATEFILTERF2.%% References:%   [1] Kamarainen, J.-K., Kyrki, V., Kalviainen, H., Gabor%       Features for Invariant Object Recognition, Research%       report 79, Department of Information Technology,%       Lappeenranta University of Technology %% Author(s):%    Joni Kamarainen <Joni.Kamarainen@lut.fi>%    Ville Kyrki <Ville.Kyrki@lut.fi>%% Copyright:%%   The Gabor Features in Signal and Image Processing Toolbox is%   Copyright (C) 2000 by Joni Kamarainen and Ville Kyrki.%% Check filter size parameterif length(n)>1,  nx=n(1);  ny=n(2);else  nx=n;  ny=n;end;% Check if different values for major and minor axes of Frequency% domain Gaussian envelopeif length(pf)>1,  pf1 = pf(1);  pf2 = pf(2);else  pf1 = pf;  pf2 = pf;end;% Set checking valuesalpha = f0/gamma;beta = f0/eta;nyqf = 0.5; % Nyquist frequency %% Checking Nyquist criterionif (f0 > nyqf)  warning('Nyquist criterion violated');end;%% Checking spatial constraints% Symmetric part of the filter must contain pt percent of the% full filter envelope % Lasketaan 'leveydet' aallon suunnassa ja aaltoa vastaan kohtisuoraanlx=max(abs([cos(theta)*nx sin(theta)*ny]));ly=max(abs([sin(theta)*nx cos(theta)*ny]));	   % Filtterin symmetrisen osan tulee sis鋖t潷 pt prosenttia fpt = abs(erf(alpha*floor((lx-1)/2))*erf(beta*floor((ly-1)/2)));if (fpt < pt)  warning(['Spatial filter size may be too small. '...	   ' Requested minimum spatial envelope size is '...	   num2str(pt*100) ' percent and current size is '...	   num2str(100*fpt)]);end;%% Checking frequency constraints% marjor axis constraintsfpf1 = erf(pi/alpha*f0);if (fpf1 < pf1)  warning(['Filter envelope insufficiently located along the major axis in the frequency domain. '...	   ' Requested minimum envelope area inside domain is '...	   num2str(100*pf1) ' percent and currently area is ' ...	   num2str(100*fpf1)]);%  warning(['Area of filter envelope along the major axis insufficient' ...%	   ' in frequency domain']); end;% minor axis constraintsfpf2 = erf(pi/(beta)*1/2);if (fpf2 < pf2)  warning(['Filter envelope insufficiently located along the minor axis in the frequency domain. '...	   ' Requested minimum envelope area inside domain is '...	   num2str(100*pf2) ' percent and currently area is ' ...	   num2str(100*fpf2)]);%  warning(['Area of filter envelope along the minor axis insufficient' ...%	   ' in frequency domain']); end;