function [X2,Y2] = dummy(X1,Y1,t,f1,f2)

%3-D PLANE PROJECTIVE GEOMETRIC COORDINATE TRANSFORMATION     Steve Mann, 1991
%
%use:  [X2,Y2] = project2(X1,Y1,t,f)
% or:  [X2,Y2] = project2(X1,Y1,t,f1,f2) % default: f1 = f2, if f2 not specified
%        X1,Y1 = original sample points 
%        X2,Y2 = new sample points
%           f  = principal distance (focal length)
%           t  = angle between the two planes
%           film assumed to be outside (in front of) camera
% assumes COP is lower left of screen

if nargin < 5  % if only one focal length specified, assume both equal
  f2 = f1;
end%if

X2 = f2*tan(ones(X1)*t + atan(X1/f1));
Y2 = f2*Y1./(ones(X1)*f1*cos(t)-X1*sin(t));