Three spiral galaxies with warped disks have been observed; NGC 4013, NGC 4565, and NGC 6504. There is a clear wavelength dependence in the warp's curve, the bluest colors presenting greater distortion. These differences cannot be due to extinction. A larger warp in the young population of stars can be clearly and directly appreciated in the NGC 4013 outskirts, where the dust lane crosses the disk defined by the galactic star background with a very different position angle. The warping curve is studied, and it is shown that it can at times be complex: in some cases, it seems to begin in the opposite hemisphere before it slowly departs from the galactic plane.