A light emission system comprising: a plurality of light emitting modules (M1, M2, M3, M4, M5, M6) each including a plurality of light emitting elements and each being a unit to be controlled; and a central controller wherein each of the light emitting modules comprises a photosensitive sensor, the photosensitive sensor being adapted to detect brightness of each of the light emitting elements in the corresponding light emitting module in a brightness detection period of the light emitting module; and each of the light emitting modules comprises a light emitting module controller, the light emitting module controller being adapted to control the corresponding light emitting module, wherein the plurality of light emitting module controllers are divided into a plurality of groups (DG1, DG2), the plurality of light emitting module controllers belonging to each of the groups are connected in a cascade manner within the group, the central controller is connected in parallel to each of the plurality of groups and adapted to transmit packet data in parallel to the groups, characterized in that, a module ID considered as an identification number is assigned to each light emitting module controller such that the light emitting modules controlled by light emitting module controllers with the same module ID are not neighboring light emitting modules, the packet data comprises a module ID and light emission control information, each light emitting module controller is adapted: - to transfer the packet data to the following light emitting module controller in the cascade arrangement such that, in each of the groups, the packet data is sequentially transferred from each light emitting module controller to any following light emitting module controller in the cascade arrangement, and - to fetch a packet data with the corresponding module ID as a control data, and - to perform a light emission control of each of the light emitting elements for a unit period of light emitting operation, on the basis of the light emission control information of the control data, so that, if the light emission control information of the control data indicates to perform the light emitting operation for brightness detection, the light emitting module controller is adapted to perform a light emission control of each of the light emitting elements belonging to the associated light emitting module such that the unit period of light emitting operation includes a period of light emitting operation of the light emitting element as a light source and includes a further period of light emitting operation synchronised with the brightness detection period, and, if the light control information of the control data does not indicate to perform the light emitting operation for brightness detection, the light emitting module controller is adapted to perform a light emission control of each of the light emitting elements belonging to the associated light emitting module such that the unit period of light emitting operation includes a period of light emitting operation of the light emitting element as a light source and includes a further period of light emitting operation timed to miss the brightness detection period, wherein the light emission system is adapted so that light emitting operation with the brightness detection is performed simultaneously for light emitting modules controlled by light emitting module controllers with the same module ID and is not performed simultaneously in neighbouring light emitting modules. a plurality of light emitting modules (M1, M2, M3, M4, M5, M6) each including a plurality of light emitting elements and each being a unit to be controlled; and a central controller - to transfer the packet data to the following light emitting module controller in the cascade arrangement such that, in each of the groups, the packet data is sequentially transferred from each light emitting module controller to any following light emitting module controller in the cascade arrangement, and - to fetch a packet data with the corresponding module ID as a control data, and - to perform a light emission control of each of the light emitting elements for a unit period of light emitting operation, on the basis of the light emission control information of the control data, so that,