Conexant’s product portfolio of multimedia ICs provide the finest combination of features, video performance, flexibility, size and value for today’s Set Top Box, PC Video, DVD playback, Digital Photography and other video systems. Key features such as 10-bit current output DACs, worldwide video standards support, interfaces with common bus architecture and compact packages provide the ultimate combination of video performance, quality, ease of design and overall value.

Graphics Standards, Colour Depth & Display Resolutions

There are many different display colour depths and resolutions. People will talk about "CGA" or XGA resolution, but what does this mean? Also the higher the resolution, the more information is stored or required, and if this
data is being transmitted over a communications link, the higher the
bandwidth required. Read on...

Usage of bandwidth can be improved by reducing the colour depth (number of bits used per pixel to encode a colour), the table below is a reference to help explain this. If live video is involved, then the bit rate required is a derivative of the frame rate, we have shown bandwidth, in the table opposite, for 25 frames per second (fps).

Standard	Horizontal Resolution	Vertical Resolution	Megapixel Resolution	Colour Depth (bits)	Bytes per frame	Kbps @ 25fps
QCIF	176	144	0.025	8	25,344	4,950
MDA	320	200	0.064	1	8,000	1,563
CGA	320	200	0.064	2	16,000	3,125
MCGA	320	200	0.064	8	64,000	12,500
CIF	352	288	0.101	8	101,376	19,800
VGA	640	480	0.307	8	307,200	60,000
NTSC	646	486	0.314	16	627,912	122,639
PAL	768	576	0.442	16	884,736	172,800
SVGA	800	600	0.480	16	960,000	187,500
XGA	1024	658	0.674	16	1,347,584	263,200
SXGA	1280	1024	1.311	16	2,621,440	512,000
SXGA	1280	1024	1.311	24	3,932,160	768,000

Obviously, 768 Mbit/s is very high bandwidth, forms of compression are normally employed (MPEG etc.) which reduce this requirement dramatically.

What effect do these different formats have on the image visually? We have shown some examples below. (There may be some limitations due to the screen reproduction).