Why doesn xv do xyz in 16bpp?
xv doesn’t cope well with 16bpp in three ways. First, it can’t grab pieces of the screen. Second, if you grab pieces of the screen with xwd and try to display them with xv, it doesn’t work well. xwud works. Third, if you display a 24bpp picture, it doesn’t bother to dither it down to 16bpp, resulting in bad pictures. You might want to consider using the GIMP, or xli.