For colour cameras, the colour information is integrated into the signal to create either PAL or NTSC signals. Trying to fit all this information down one wire naturally limits the image quality, and so for colour applications, the colour (or chrominance) information is often transmitted over a separate cable from the luminance (monochrome) signal. This system is known as the S-Video standard. To maintain the best possible colour image quality using analogue technology, each colour signal uses a separate channel, requiring 3 cables: one each for Red, Green and Blue. This interface is called RGB. Within the vision industry there is also an additional requirement to support dynamic exposure control and asynchronous triggering. To achieve these, the timing signals are usually separated from the video signal and this additional exposure control requires two or three extra cables.
Although there are no official standards, the Hirose connector has become the de-facto standard for analogue vision cameras, making interfacing relatively easy. In the digital era analogue cameras are generally not specified in new applications.