How to read the value of a point in the FFT and Complex output windows

Readings the output of the FFT of the picture of a circle in ImageJ at some random point (163,128) I get X_{\text{Re}}=-0.182 and X_{\text{Im}}=-3.854, using the Complex plot (yellow dot). The value on the output on the FFT plot is 32 (cross cursor symbol):


I don’t understand why the relation between this latter value (32), which I presumed it was the amplitude, and the real and imaginary components, i.e. \vert X[k]\vert=\sqrt{X_\text{Re}^2+X_\text{Im}^2}, is not fulfilled.

Good day Toni,

in order to cope with the high dynamics of Fourier-spectra, ImageJ shows the power spectrum with logarithmic values.

More information is in the ImageJ manual:
https://imagej.nih.gov/ij/docs/guide/146-29.html#toc-Subsection-29.10

Have a nice weekend

Herbie