Graphic Cards

by [Published on 20 March 2008 / Last Updated on 20 March 2008]

An overview of graphic cards, why they are important in some businesses, and some common features.

In many businesses today, graphics play an increasingly important role. TV, movie, and video game production companies are obvious examples of businesses which require high quality graphic cards to support their needs. Other, less obvious, examples require the same attention be paid to their graphic cards. Some of these businesses might be large industrial companies which require complex control and monitoring system. These systems are, more and more, incorporating complex graphics, charts, and video, which leads to the need for adequate graphic cards.

Other businesses are beginning develop a requirement for high performance graphic cards as well. This is due, in large part, to the growth in online meeting and collaboration tools. Whatever the business your network enables it is important for the network administrator to have a good understanding of graphic cards. Even if the business does not fall into any of the categories I've mentioned above, it is important to be knowledgeable of graphic cards so that you will purchase the equipment suitable for your network.

The advantage a graphic card gives your computer is that the processing of all graphics happen off of the motherboard. Many motherboards do have a built in capability to handle two dimensional images. This is sufficient for web-browsing and creating documents and is probably adequate for many business needs. Some businesses require more.

Moving the processing of graphics off of the motherboard requires a separate printed circuit board which connects to the motherboard. The graphics printed circuit board (at what point does it become a graphics card?) connects to the motherboard in the same way as I described in a previous article titled, Memory and Storage - Part 3: Bus Specifications.

To make this printed circuit board a graphics card we need a few things. Most importantly we need a Graphics Processing Unit (GPU). The GPU is very much like the computer's CPU except that is optimized for the mathematical operations commonly seen while processing graphics. This optimization is the main difference between many GPUs on the market. To be honest, only the most demanding graphics needs would require you to pay much attention to these differences. Simply having the graphics processed in a GPU which has been optimized at all will most likely give you all that is needed.

Another element required by graphics cards is memory. The GPU uses this memory to temporarily store information it needs to process the graphics in an efficient manner. This memory can also be used as a buffer to store images which need to be displayed soon. The amount, and type, of memory used by the graphics card is important. To read about the right memory that can provide performance improvements, see my previous articles titled, Memory and Storage.

A graphics card also needs a way to connect to the monitor. Most graphic cards have a RAMDAC. The RAMDAC is a dedicated Digital to Analog (DAC) for the RAM to connect to an analog monitor like the traditional CRT monitors. The RAMDAC, as its name implies, converts the digital information into an analog signal. Some graphic cards may even have multiple RAMDACs which allow the card to support multiple monitors.

Most of today's graphic cards also have DVI output slots which are used to connect to an LCD monitor. It is also common to see additional output slots such as S-Video, component video, or HDMI. These additional slots can be convenient if you want to use a TV as a monitor or a projector.


Figure 1: Graphic card connectors courtesy of http://en.wikipedia.org/

I like to think of the graphics card as a secondary motherboard. It has a processor, memory, inputs and outputs, a BIOS, it requires power (either from the motherboard or the power supply), and has its own cooling system. The cooling system is normally a heat sink but could be any of the systems I described in my previous article titled, Computer Cooling Technologies.

Like a motherboard, there are numerous standards for graphic cards. Two common standards you are likely to see are API standards called Direct3d and OpenGL. Direct3d is a Microsoft proprietary API compatible with Windows operating systems (and the XBox). OpenGL is an open, cross-language, cross-platform API. Both of these APIs expose the two dimensional and three dimensional capabilities of GPUs and allow software developers to easily utilize advanced capabilities.

Anti-aliasing

One of these advanced capabilities available in most graphic cards is called anti-aliasing. In this context, anti-aliasing will "smooth out" the graphics and make an image look true. Although correct, this explanation really doesn't do anti-aliasing justice. Within the realm of digital signal processing, anti-aliasing is a well known technique. A full and detailed explanation isn't appropriate for this article, but if you'd like to know more send me an email and I'll point you to some further reading.

High dynamic range rendering

HDR rendering is another advanced feature found in many quality graphic cards. This type of rendering provides two important abilities related to light. First, both very light and very dark areas can contain detailed graphics which produces sharper images as seen in Figure 2. Second, reflection of light can have the same brightness as the light source. This produces more realistic images, as can be seen in Figure 3.


Figure 2: Comparison between HDR and LDR (Courtesy of http://en.wikipedia.org/)


Figure 3: How light is reflected (Courtesy of http://en.wikipedia.org/)

Texture mapping

Texture mapping is an ability where the GPU can apply a previously calculated texture, or pattern, to a surface. This texture is then mapped to this surface. This is an advantage because the texture does not have to be recalculated and redrawn every time the surface is redrawn.

Fresnal equations

The Fresnal equations describe the reflection of light off of different surfaces. Advanced graphic cards have these equations available to programmers. Apple's iChat makes good use of this capability. Having this capability means that the program does not have to continuously calculate and display the reflections. A significant amount of processing power can be freed up by using this feature.

Blurring

Many graphic cards also have the ability to automatically blur images not in a predefined depth of field. This means that images behind and in front of the main image are automatically blurred. Motion blurring, as it's name implies, can automatically blur images which are moving.

These advanced capabilities, and the many others, do one of two things. They either make computer generated graphics more realistic and/or detailed, or they significantly simplify and speed up the rendering of complex graphics (like reflections or textures). All of this leads to improved performance for the user.

Many of the advanced capabilities I described in this article are quite complex. I encourage you to read up on these capabilities because they are all quite interesting. As always, if you have any questions don't hesitate to send me an email.

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