[alecst]

What do you mean?

[frozenport]

The imaginary part of the transform.

[nphrk]

The article uses the magnitude of the coefficients, which is computed using both the real and the imaginary part.

[dbaupp]

The phase portion isn't actually just the imaginary part, it's just the piece of information lost when one goes from real+imag -> magnitude, i.e. it's the argument of the complex number.