Is spectral centroid enough to measure brightness? i'm new in this group and i'm studying a sound signal.
I have used FFT for extrapolate frequencies and see the harmonics of this sound.
I have to compare this sound with another similar sound and find the diffrences.

From various research I found that an important element that characterizes a sound, and therefore it's timbre is the brightness.
My question is:
is it sufficient to calculate the brightness using only the specrtal centroid, using the frequencies and the 'magnitude' of my fft?
'Brightness' is a subjective descriptor of an audio signal. It can't be calculated directly from physical properties of the signal. A panel of subjects can give you their ratings for brightness of one signal relative to another. 

That said, the spectral centroid has long been known to be correlated with subjective measures of brightness. So while you are not calculating brightness itself you should be calculating a fairly good indicator.