Investigation of the breakdown and early warm-up of high-intensity-discharge (HID) lamps demands appropriate imaging techniques due to short time scales of the ignition processes and initially poor optical conditions. High-speed cameras are able to access these phases and give additional information needed for theoretical modeling and HID design, which is focused on instant light and reduced ignition voltage. This work presents optical measurements on a 200-W HID mercury lamp ranging from ignition to steady-state operation, showing typical evolution stages of the warm-up process.