What is the function of AntonB in this program?

function y = dtdwt(x) windowsize = 7; windowfilt = ones(1,windowsize)/windowsize; % Number of Stages J = 6; I=sqrt(-1); L = length(x); N = L+2^J; x = symextend(x,2^(J-1)); load nor_dualtree [Faf, Fsf] = AntonB; [af, sf] = dualfilt1; W = dual2D(x, J, Faf, af); W = normcoef(W,J,nor); % Noise variance estimation using robust median estimator.. tmp = W{1}{1}{1}{1}; Nsig = median(abs(tmp(:)))/0.6745; for scale = 1:J-1 for dir = 1:2 for dir1 = 1:3 Y_coef_real = W{scale}{1}{dir}{dir1}; Y_coef_imag = W{scale}{2}{dir}{dir1}; Y_parent_real = W{scale+1}{1}{dir}{dir1}; Y_parent_imag = W{scale+1}{2}{dir}{dir1}; Y_parent_real = expand(Y_parent_real); Y_parent_imag = expand(Y_parent_imag); Wsig = conv2(windowfilt,windowfilt,(Y_coef_real).^2,'same'); Ssig = sqrt(max(Wsig-Nsig.^2,eps)); % Threshold value estimation T = sqrt(3)*Nsig^2./Ssig; % Bivariate Shrinkage Y_coef = Y_coef_real+I*Y_coef_imag; Y_parent = Y_parent_real + I*Y_parent_imag; Y_coef = bishrink(Y_coef,Y_parent,T); W{scale}{1}{dir}{dir1} = real(Y_coef); W{scale}{2}{dir}{dir1} = imag(Y_coef); end end end what Nsig and Ssig and eps are calculating?

[Ahmed A. Selman]

AntonB is a user defined function. Please use formatted syntax for clearer viewing of the question.

Nsig is the median of the absolute of variable (tmp) from:

   Nsig = median(abs(tmp(:)))/0.6745

and Ssig is:

   Ssig = sqrt(max(Wsig-Nsig.^2,eps))

sqrt finds the square root.. and (eps)in

   max(Wsig-Nsig.^2,eps)

is used to tell (max) to compare and generate any maximum larger than eps (the spacing for floating number, usually less than ~ 10^-15 in Matlab).

Answer 1

[Wayne King]

AntonB is a function that returns the scaling and wavelet filters that are used in the dual tree wavelet transform.