complex numbers - Geometrical interpretation of $ Im(z^4) ge 0$

I'd like to ask you about a geometrical interpretation of the expression like $Im(z^4) \ge 0$.

What I did:

$Im [r^4(cos4α + isin4α] \ge 0$

$r^4sin4α ≥ 0$

$sin4α \ge 0$

$4\alpha = k \cdot \pi$, k is integer

$\alpha = k \cdot \frac{\pi}{4}$

But how to draw it on argand diagram?
Is there any tool online? Is it possible on Wolfram Alpha?

Is it something like this?

Geometrical interpretation

Answer

Credits to Marconius.

The plot was made with Mathematica:

ContourPlot[Im[(a + I b)^4], {b, a} \[Element] Disk[], 
   PlotTheme -> "Monochrome", PlotPoints -> 50, 
   Contours -> #] & /@ {1, 5, 10}