The present invention generally relates to a lighting system comprising LED modules (10, 20), arranged adjacent to each other, preferably in a matrix configuration. By introducing light apertures (101) between two or several adjacent modules, each comprising a mixing chamber (11, 21), light is transmitted sideways between the mixing chambers of the adjacent modules, whereby the perceived lighting from the associated module windows is equalized. Hence, the invention facilitates an homogenization of perceived illumination without the need for an electronic control system.