What is a Video Card?
A video card, display adapter, graphics accelerator or graphics card is simply an expansion card (a piece of circuit board that plugs into a computers main board) that takes digital signals and turns it into graphical interpretation on a computers monitor or screen.
How do Video Cards Work?
The computers processor works with software (Games, Graphic Design applications, DVD decoders etc...), sends information about the image to the Video Card. The Video Card decides how thepixles on the screen will act together create the image(Rendering). When this is done the information is sent to the Monitor for viewing through a cable.
- Bit Blits, this is one of the most important functions of the video card. A bit blit is simply like when dragging an icon or scrolling text, we still want to see its still be there and not get blurry. This is a bit blit.
- Line Drawing, in this operations you are able to draw an lines and have it recognized by the start and end points rather than in a single pixle. This is very important for persons who are into CAD/CAM and other activites thar require Vector Graphics
- Color and Pattern, when drawing we want to fill in the spaces from beginning to end. 2D Acceleration allows a part of the screen to be updated seperately that wouldn't be possible if the whole image is one pixel.
- Clipping is a fast way of showing an object that obscures another. We want it fast and look smooth.
- Off Screen Caching, this allows for regularly used graphics such as fonts to be pulled up fast without going to main system memory every time.
- The Geometry, we know what a triangle is like, right? your CPU has the job of determining were the triangle have to be placed to make an object on screen. This is usually done over a wire frame as seen in Auto CAD programs.
- Transform, now we have to put these triangles together. Your CPU will put a model of this image together in system memory on a wire frame. Not only this but we have to figure out the lighting of the triangles while in memory. This usually occurs on your systems CPU and not on the Video card processor.
- Render, now after taking information out of memory it is most likely sent to the Video Cards processor. When information hits the graphic board processor we will put those Bit Map images over our triangles thus making an image in 3D.
- This is just a basic example of course. In some of those steps especially after the transform you can see were the Double buffering comes into play under Direct Draw. Now lets look at some more steps that can come into play with 3D operations. This is added to the basic steps above to make for a better scene.
- Filter, this is Bi-linear and Tri-linear filtering. This is done by smoothing over those blocky bitmaps. Textures will seem more streamline and realistic. If you play Quake II you know what I mean. If you have played Quake I you are also a witness to the blocky square looking graphics.
- Double Buffering, as we discussed earlier. We need to display a scene and work on one at the same time. This will give you a streamline appearance. If your buffering is out of whack you will know it soon.
- Flat Shading, this is similar to the filters above. We are taking those triangle with color and more or less bleeding them together. This really adds more to the realism rather than a red block here and a blue block next to it.
- Mipmapping, this is overlooked but very important in game play. Let say your walking inside a scene towards dog, you want the dog to be bigger than what you seen it a mile away if you are standing right in front of it. This is mipmapping. Textures are basically swapped while moving to ad more realism to the scene. Cool huh!?
- Atmosphere, if your dog in the scene above is smoking a cigarette we also want to see the hazy smoke. This is were the atmosphere can come into play. On flight simulators you will see haze or fog while flying this is another example of atmosphere.
- Lighting, this effect will light up the dog so you can see it or even make his cigarette flare a little. Your dog may even show the light intensify on his snout along with the haze over him, this is were lighting comes in.
- Z-Buffering, this comes down to objects that are obscured by another. We don't want to draw that part of the scene until it is moved. This is another way of improving performance.
Graphic Processing Unit
A graphics card's processor, called a graphics processing unit (GPU), is similar to a computer's CPU. A GPU, however, is designed specifically for performing the complex mathematical and geometric calculations that are necessary for graphics rendering.
Used primarily for 3-D applications, a graphics processing unit is a single-chip processor that creates lighting effects and transforms objects every time a 3D scene is redrawn. These are mathematically-intensive tasks, which otherwise, would put quite a strain on the CPU. Lifting this burden from the CPU frees up cycles that can be used for other jobs.
Some of the fastest GPUs have more transistors than the average CPU. A GPU produces a lot of heat, so it is usually located under a heat sink or a fan.
|Video Standard||Full Name||Display Resolution||Ratio|
|VGA||Video Graphics Array|| 640×480 (307k)
|SVGA||Super VGA||800×600 (480k)||4:3|