a camera adjusts its strobe energy to achieve proper exposure of a photograph . the adjustment method uses two trial exposures of the scene to be photographed . one trial exposure is taken without the camera strobe using only ambient illumination . the other trial exposure is taken using the camera strobe at a pre - set energy level . pixels that appear as saturated in the ambient - only trial exposure are discounted in the determination of the strobe energy for the final photograph . this method properly exposes scenes which themselves contain bright light sources such as lamps or light fixtures .