Appendix:
VIDEO CONFERENCE GLOSSARY
CMOS image sensor -
CMOS (abbreviated for
Complementary Metal
Oxide Semiconductor
) is similar to CCD with different silicon process in production.
The advantage of CMOS is low power consumption, low production cost and small in
chipset dice. The cons are lacking of noise immunity, which leads to less sensitivity in
image quality. The modern silicon technology, however, can improve the
signal-to-noise ratio significantly. Major suppliers of CMOS sensor are: OmniVision,
VLSI Vision, Rockwell, Sharp, HP, Sony, and EleVision with resolution start from
80,000, 250,000 to 1,000,000 pixels.
Digital PC Camera -
Digital PC camera, on the other hand, sends the
digitized video signal, so-called YUV format, directly to your PC through parallel port,
COM port, USB port, Fast Ethernet or IEEE 1394 interface. CCIR 601, a digital TV
encoding standard, defines video digitized signal in YUV 4:4:4, or YUV 4:2:2 format.
A corresponding driver in PC will decode and translate the data into correct color for
splay. Digital camera is dedicated, but not limited, for PC applications today. The most
popular interface today are parallel port and USB port.
Image DSP -
Image DSP is used to deal with the image and color captured and
ensure sharpness of color displayed on monitor. Image DSP can control white balance,
hue and saturation of RGB color, gamma value for color adjustment. Different
algorithms are implemented in DSP to provide such functions. Some silicon suppliers
has already integrate DSP together with image sensor as one-chip solution for
cost-down reason, while others implement compression engine in image DSP to speed
up the data transmission rate.
