calculating energy of an image

I have a code for dual tree 3D,in that i want to calculate energy for each subband ,please help how to calculate energy

   x = rand(64,64,16);
    J = 1;
    [Faf, Fsf] = FSfarras;
    [af, sf] = dualfilt1;T=10;
    w = dualtree3D(x, J, Faf, af);
  y = idualtree3D(w, J, Fsf, sf);

Answer 1

[Wayne King]

You can calculate the energy as follows

    x = rand(64,64,16);
    J = 1;
    [Faf, Fsf] = FSfarras;
    [af, sf] = dualfilt1;T=10;
    w = dualtree3D(x, J, Faf, af);
    details = w{1}{1}{1};
    energy = sum(abs(details(:)).^2);

w{2}{:}{:} contains the approximation coefficients

[kash]

Thanks a lot wayne another question ,with this same code i have added noise shaping code and have found energy for each subbands,now i want to plot bar graph for energy and energ1,showing the variation before and after noise shaping,please help how to plot ,i am confused because each subband contains more than one value

[Wayne King]

after you computed the energy there is more than 1 value?

details = w{1}{1}{1};

energy = sum(abs(details).^2);

The above (energy) is a scalar.

[kash]

i get 32 values for each subband,please tell how to plot for it

[PRAKASH BHARTI]

what is the unit of above calculated energy please specify