Fujitsu Develops SmartCODEC™ Streamlined Image Compression Technology for Automotive Applications

Kawasaki, September 21, 2006

Fujitsu Laboratories Limited today announced that it has developed image compression technology for automotive use that complies with the IDB-1394 (ITS Data Bus-1394)⁽¹⁾ standard for in-vehicle digital imaging transmission system networks. The new technology, SmartCODEC, features a compression rate of one-third (1/3), and a fast compression-decompression time of just 2 to 3 milliseconds that enables compression and multiplex transmission of images to inside the vehicle, such as images from multiple automotive cameras located externally on the vehicle. In addition to assisting facilitation of safer driving through these functions, Fujitsu's new technology also makes it possible to reduce the amount of cable required within the vehicle to achieve fast and high-quality image transmission of multiple images.

Details of the newly-developed technology are scheduled to be presented at the Institute of Electronics, Information and Communication Engineers (IEICE) conference being held in Kanazawa, Japan from September 19.

Background

There is an increasing need to use multiple video channels in automobiles, such as for video images from multiple surveillance cameras that the driver checks on the monitor, as well as navigation system images and DVDs for passengers watching on rear-seat monitors. Analog signals which have been used thus far required a separate cable to be wired for each channel, a process that has become complicated as the number of channels has increased. This has resulted in demand for a technology capable of multiplex transmission of images on a single in-vehicle LAN.

Technological Challenges

Even with the IDB-1394 image transmission standard (featuring transmission speeds of 400Mbps), bandwidth is insufficient for uncompressed transmission of multiple images, and therefore there is a need for image compression technology. Developing such technology for automotive use has entailed overcoming three challenges: making low-cost packaging for each compression and decompression channel; achieving a transmission delay time of less than 30 milliseconds for surveillance cameras used when the vehicle is being driven; and achieving clear reproduction of letters and lines on images transmitted for car navigation systems. In image compression methods used thus far, such as MPEG, external memory was required for compression-decompression of large-scale integrated circuits (LSIs) thereby leading to higher cost, and in addition, the compression-decompression delay time of several hundred milliseconds had to be overcome. Furthermore, conventional methods mainly used natural images, and there were concerns about poor image quality for car navigation systems, such as broken or indistinct letters.

Newly Developed Technology

The newly-developed SmartCODEC is compression technology dedicated for in-vehicle image transmission. It offers as an industry's first, three features unavailable in conventional technology for in-vehicle image transmission: light weight, minimal delay time and high image quality. In order to lighten the circuitry, the compression ratio was limited to one-third (1/3), and a differential pulse code modulation (DPCM)⁽²⁾ scheme featuring simple structures was adopted. In addition, in order to clearly reproduce camera images and the edges of letters and lines on the navigation system, the modulation level is optimized at the pixel unit. By encoding pixels in groups of two, the processing speed was accelerated without increasing the basic clock speed, enabling minimal delay time.

SmartCODEC Specifications

• Target images:
  Natural images, letter and line drawings, YUV 720 x 480 pixels; RGB 800 x 480 pixels, etc.
• Processing speed:
  Maximum: 60 frames/second; equivalent to RGB 800 x 480 pixels
• Minimal delay time:
  Compression-decompression time is 2 to 3 milliseconds
• Design convenience (lightweight circuitry):
  Circuit can be closed in an IDB-1394 controller LSI; external memory not required
• Compression ratio:
  Fixed ratio of 1/3; YUV 720 x 480 pixels; transmission rate: 55 Mbps for 30 frames/second

Results

This technology is a lightweight circuit that can be enclosed in the IDB-1394 controller developed by Fujitsu, enabling a one-chip automotive image transmission network and compression-decompression solution. It makes possible low-cost multiplex transmission of images in automobiles with minimal delay time.

Future Developments

This technology is scheduled to be commercialized by Fujitsu Limited in early 2007.