The structural parameters of a magnitude-limited sample of 148 unbarred S0-Sb galaxies were derived to study the correlations between bulge and disk parameters as well as the probability distribution function ( PDF ) of the intrinsic equatorial ellipticity of bulges .
A new algorithm ( GASP2D ) was used to perform the bidimensional bulge-disk decomposition of the J -band galaxy images extracted from the archive of the 2MASS survey .
The PDF of intrinsic ellipticities was derived from the distribution of the observed ellipticities of the bulges and misalignments between the the bulges and disks .
About 80 \% of the observed bulges are not oblate but triaxial ellipsoids .
Their mean axial ratio in the equatorial plane is \langle B / A \rangle = 0.85 .
There is not significant dependence of their PDF on morphology , light concentration or luminosity .
This has to be explained by the different scenarios of bulge formation .