The present invention provides an inductive transmission system for inductive transmission of power and full duplex data signals between a first device and a second device. The invention further relates to a process for preparing these metallic effect pigments, to a coating composition, and to a coated article. The black data ratio is compared with at least one reference ratio, and an error diffusion function for the video data is controlled according to the compared result. The techniques may be useful for perpendicular patterned media, i.