NTSC DV is 4:2:0, which means one chroma channel is sampled at just half the resolution of the luma (i.e. 2 pixels share common colour info in this channel) and the other channel is sampled at half that of the first chroma channel (i.e. 4 pixels share common colour info in that channel). Compare with RGB—or even 4:4:4 planar formats—which stores 24 bits for each pixel.
NTSC DV is 4:2:0, which means one chroma channel is sampled at just half the resolution of the luma (i.e. 2 pixels share common colour info in this channel) and the other channel is sampled at half that of the first chroma channel (i.e. 4 pixels share common colour info in that channel). Compare with RGB—or even 4:4:4 planar formats—which stores 24 bits for each pixel.