%compute invariant moments of image
function phi =invmoments(F)
if (ndims(F) ~= 2) | issparse(F) | ~isreal(F) | ~(isnumeric(F) | islogical(F));
    error(['F must be a 2D,real,nonsparse,numeric or logical matrix.']);
end
F=double(F);
phi =compute_phi(compute_eta(compute_m(F)));