A real-time color-intensity modulation multi-input-multi-output (CIM-MIMO) optical camera communication (OCC) system is designed and implemented. It utilizes multiple intensity levels for each color and 3 colors of each RGB LED module of a LED array, to generate M-ary CIM symbols. Signal constellation and training sequences are designed to tackle the system imperfectness. Applying 256-CIM to 192 data-carrying LEDs of a commercial 16 × 16 LED array at a refresh rate of 82.5 Hz and a mobile phone camera at a frame rate of 330 fps, the system achieves a data rate of 126.72 kbps over 1.4 m, without external optical assistance.