An elevator safety system includes: at least two sensors, each of the sensors being configured for monitoring at least a portion of a hoistway of an elevator system and providing monitoring signals; a transformation unit which is configured for transforming the monitoring signals provided by at least one of the sensors and producing transformed signals corresponding to a common direction of vision; a comparison unit which is configured for comparing the at least two transformed signals and for generating a failure signal if a difference between the at least two transformed signals exceeds a predetermined threshold; and a detection unit, which is configured for detecting a person or undesired item in at least one of the two transformed signals and for generating an alarm signal if a person or undesired item is detected.