  We present the morphological analysis based on HST-NIC2 (0.075 arcsec/pixel)
images in the F160W filter of a sample of 9 massive field (> 10^{11} M_\odot)
galaxies spectroscopically classified as early-types at 1.2<z<1.7. Our analysis
shows that all of them are bulge dominated systems. In particular, 6 of them
are well fitted by a de Vaucouleurs profile (n=4) suggesting that they can be
considered pure elliptical galaxies. The remaining 3 galaxies are better fitted
by a Sersic profile with index 1.9<n<2.3 suggesting that a disk-like component
could contribute up to 30% to the total light of these galaxies. We derived the
effective radius R_e and the mean surface brightness <mu_e> within R_e of our
galaxies and we compared them with those of early-types at lower redshifts. We
find that the surface brightness <mu_e> of our galaxies should get fainter by
2.5 mag from z~1.5 to z~0 to match the surface brightness of the local
ellipticals with comparable R_e, i.e. the local Kormendy relation. Luminosity
evolution without morphological changes can only explain half of this effect,
as the maximum dimming expected for an elliptical galaxy is ~1.6 mag in this
redshift range. Thus, other parameters, possibly structural, may undergo
evolution and play an important role in reconciling models and observations.
Hypothesizing an evolution of the effective radius of galaxies we find that R_e
should increase by a factor 1.5 from z~1.5 to z~0.
