For three cameras, camera tube with three images must be accurately coincide together, to get a high definition, restore color accurate images. But because of the camera tube can't be identical, and where it is difficult to place very precise, so the coincidence error would be generated.
Road in red or blue channel relative to the green-channel offset is expressed as a percentage of the screen height. Tube type by region: I: 0.05% II: 0.1% III: 0.15%. Chip: the region is less than 0.05%.