The present invention provides synchronization and control between the wavelength of a multi-wavelength illuminator and the image frames acquired by a video camera. In accordance with the present invention, the trailing edge of a camera expose-signal triggers a pre-loaded digital value to be output from a FIFO buffer. The digital value selects a particular illumination wavelength either directly or through a voltage from a digital to analog converter. The FIFO may be periodically refilled, or it may be a circular register.