Fujitsu Laboratories Ltd. has developed IDB-1394 (ITS data bus-1394)-compliant image compression technology called SmartCODEC for in-vehicle digital image transmission. It expects to have the technology – a single-chip automotive image transmission network and compression/decompression solution – commercialized by early next year.
The need for multiple video channels in automobiles is increasing due to video images from multiple surveillance cameras, navigation system images and rear-seat entertainment. IDB-1394, at 400 Mb/s, is insufficient for uncompressed transmission of multiple images, and analog signals require a separate cable for each channel, thus there is demand for a technology capable of multiplex transmission of images on a single in-vehicle LAN.
That technology requires 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.
According to Fujitsu, external memory is required for compression-decompression of large-scale integrated circuits (LSIs) in current image compression methods such as MPEG, and compression-decompression delay times range up to several hundred milliseconds. Conventional methods raised concerns about poor image quality for car navigation systems, such as broken or indistinct letters.
Fujitsu’s SmartCODEC promises a one-third compression rate and 2-3 millisecond compression-decompression time for fast, high-quality transmission of multiple images. The technology can help make driving safer while reducing the amount of cable required for image transmission.
Fujitsu said SmartCODEC offers light weight (the compression ratio was limited to one-third in order to lighten the circuitry), minimal delay time, and high image quality. Processing speed was accelerated without increasing basic clock speed, and delay time minimized, by encoding pixels in groups of two. The technology uses a differential pulse code modulation (DPCM) scheme that features simple structures, and the modulation level is optimized at the pixel unit in order to reproduce camera images and the edges of letters and lines on the navigation system.