1. A vehicular imaging system for determining roadway width comprising: an image sensor configured for capturing images; an image processor configured for receiving captured images; wherein the image sensor configured to view forward of a vehicle, such that a field of view of the image sensor includes the roadway and roadway marker signs on both the right side and left side of the roadway; wherein the image processor is configured to determine roadway width by identifying roadway marker signs in processed images that are captured by the image sensor and determine a distance from the roadway marker signs; wherein the processor is further configured to use the road width for controlling a driver assist function on the vehicle; wherein the driver assist function is at least one of a headlamp control function, a traffic sign recognition (TSR) function, and a lane departure warning (LDW) function; and wherein the image processor is one of an application specific integrated circuit (ASIC) and a field programmable gate array (FPGA).