Automotive safety is an issue that affects drivers all around the world. In the U.S.,automobile manufacturers and governments are at the forefront of integrating new technologies into next-generation cars with the aim of enhancing driver, passenger and pedestrian safety.

In a 2014 mandate from the U.S. National Highway Traffic Safety Administration (NHTSA), starting in 2018, all new vehicles sold in the country weighing less than 10,000 pounds must be equipped with rearview cameras and displays that provide the driver with vision behind the car. The push for this legislation began more than 15 years ago, initiated by a distraught father who had accidentally backed over and killed his toddler in his driveway. This father’s efforts and those of other advocates for auto safety eventually resulted in the Cameron Gulbransen Kids Transportation Safety Act of 2007, which was signed into law by President George W. Bush in February 2008.

The accident that killed Cameron Gulbransen was not an anomaly. According to a 2008 NHTSA report to the House Committee on Transportation and Infrastructure and the Senate Committee on Commerce, Science, and Transportation, between 2002 and 2006 there were an estimated 292 annual back-over fatalities and an estimated 18,000 annual back-over injuries. This research helped convince Congress to expand the Cameron Gulbransen Kids Transportation Safety Act, which led to the rearview camera and display mandate, which was initially set to go into effect in 2014 but was pushed back to 2018. The NHTSA estimates that once every U.S. car has a rearview camera, between 58 and 69 lives will be saved each year

While these statistics and mandates reflect the situation in the U.S.,the underlying implications also impact developing nations such as China and India, where automobile-safety mandates are currently limited to rearview mirrors. It can be assumed that rearview camera systems would result in a similar positive impact on vehicle safety in regions where mandates are not yet in effect.

Despite the lack of a mandate, many automobile manufacturers around the world have been making rearview systems available in their vehicles. This option was offered beginning with the luxury segment, and later rolled out as a standard feature in mainstream models. Between 2008 and 2011, the proportion of new cars sold with rearview cameras more than doubled, from 32 percent to 68 percent. While the fatality rate from back over accidents dropped 31 percent, over all injuries fell by only eight percent, which was far lower than expected.Why?

While user error for rearview camera systems is considered largely to blame for the underwhelming decrease in back-over injuries, upgrading the camera technology could have a great impact on effectiveness.

Improving Rearview Camera Systems
While user error for rearview camera systems is considered largely to blame for the underwhelming decrease in back-over injuries, upgrading the camera technology could have a great impact on effectiveness.

Most of the automobile rearview cameras on the road today were constructed using NTSC video technology. Named for the National Television System Committee, NTSC is an analog television standard that was used in the Americas and most Asia-Pacific countries until the conversion to digital television took place. NTSC cameras deliver low-resolution video, very similar to VGA picture quality, which is 640 x 480 resolution. Because of these limitations, NTSC video cameras do not provide enough resolution to accurately display the scene behind the car when a driver is backing up. Also, the camera’s location on the vehicle - generally, positioned under the license plate-does not capture a wide-enough field of view (FOV).

One solution for increasing the overall effectiveness of rearview camera systems is to improve the video quality. Thanks to recent developments in high-definition (HD) image sensing and video-processing technologies, HD cameras that offer both a higher resolution and wider FOV are a viable and increasingly cost-effective alternative to NTSC video cameras.

Overcoming HD Challenges
HD technology is not without its challenges. Achieving HD-quality resolution for automotive applications requires image sensors with a minimum of 1.3 megapixels. To maintain the existing size and cost of the camera module, the pixel area array must fit into the same size optics specified for NTSC rearview camera systems. This requires shrinking the pixels to 25% of their usual size.

Another consideration when transitioning from NTSC to HD imaging is the associated display technology. While sufficient display technology is available on the market, its high cost means that it’s unlikely to be adopted overnight for standard vehicles; particularly in developing nations.

Conclusion
Traditionally, because NTSC image sensors were a cost-effective option that served the purpose, they have been widely used in automobile rearview cameras. By providing a combined low-cost HD image sensor and ISP solution, OmniVision is empowering its customers to improve automotive rearview camera technologies that will further reduce back over incidents.