— Many approaches for extracting landmarks and objects from a camera image based on their color coding were published in the RoboCup domain. They are quite sophisticated and tuned to the typical RoboCup scenario of constant bright lighting using a static subdivision of the color space into different color classes. However, such algorithms will soon be of limited use, as the future requirements of RoboCup include the possibility to play under changing and finally natural lighting. This paper presents an algorithm for automatic online color training, which is able to robustly adapt the mapping of colors to color classes onto different lighting situations online. Using the ACT algorithm a robot will be able to play a RoboCup match while the illumination of the field varies.