How Do Computer Graphics/Video Cards Work?


Well, If you’re a gamer or just someone
who has a really nice spec’d out PC you would have probably already heard the term
‘’Graphics Card’’ and most likely you know exactly what it is used for. But how exactly does it work? What causes the Graphics card to work how
it does. Well, in this video, I’ll be talking about
just that and I hope you learn something new. So, why don’t we jump into it. Now before we get into how graphics card work,
let’s first set up a base as to what a graphics card is. Your Computer’s graphics card is the component
responsible for producing the visual output from your computer. Virtually all programs produce visual output;
the video card is the piece of hardware that takes that output and tells the monitor which
of the dots on the screen to light up (and in what colour) to allow you to see it. Now, The CPU, working in conjunction with
software applications, sends information about the image to the graphics card. The graphics card decides how to use the pixels
on the screen to create the image. It then sends that information to the monitor
through a cable. Either a classic VGA Cable or a HDMI Cable,
but in most cases with newer Cards, People tend to use HDMI Connectors. Creating an image out of binary data is a
demanding process. To make a 3-D image, the graphics card first
creates a wire frame out of straight lines. Then, it rasterizes the image (fills in the
remaining pixels). It also adds lighting, texture and color. For fast-paced games, the computer has to
go through this process about sixty times per second. Without a graphics card to perform the necessary
calculations, the workload would be too much for the computer to handle. One of the main things that a graphics card
needs is memory. The memory holds the color of each pixel. In an extremely simple situation where your
display resolution would be 640×480 and you would have a black and white screen, each
pixel may be only black or white, so you need just 1 bit to store each pixel’s color. Since a byte holds 8 bits, you need (640/8)
80 bytes to store the pixel colors for one line of pixels on
the display. You need (480 X 80) 38,400 bytes of memory
to hold all of the pixels visible on the display. The second thing a graphics card needs is
a way for the computer to change the graphics card’s memory. This is normally done by connecting the graphics
card to the card bus on the motherboard. The computer can send signals through the
bus to alter the memory. There are situations where your refresh rate
is 60 frames per second. This means that the graphics card scans the
entire memory array 1 bit at a time and does this 60 times per second. It sends signals to the monitor for each pixel
on each line, and then sends a horizontal sync pulse; it does this repeatedly for all
480 lines, and then sends a vertical sync pulse. When a graphics card handles color, it does
it in one of two ways. A true-color card devotes 3 or 4 bytes per
pixel (4 bytes allows an extra byte for an “alpha channel”). On a 1600×1200-pixel display, this adds up
to about 8 million bytes of video memory. The other alternative is to use 1 byte per
pixel and then use these bytes to index a Color Look-Up Table (CLUT). The CLUT contains 256 entries with 3 or 4
bytes per entry. A modern card contains its own high-power
central processing unit (CPU) that is optimized for graphics operations. Depending on the graphics card, this CPU will
be either a graphics coprocessor or a graphics accelerator. Think of a coprocessor as a co-worker, and
an accelerator as an assistant. The coprocessor and the CPU work simultaneously,
while the accelerator receives instructions from the CPU and carries them out. In the coprocessor system, the graphics card
driver software sends graphics-related tasks directly to the graphics coprocessor. The operating system sends everything else
to the CPU. With a graphics accelerator, the driver software
sends everything to the computer’s CPU. The CPU then directs the graphics accelerator
to perform specific graphics-intensive tasks. For example, the CPU might say to the accelerator,
“Draw a polygon with these three vertices,” and the accelerator would do the work of painting
the pixels of the polygon into video memory. I could probably go a little bit more in depth
but this is meant to be a somewhat simple video to people who are curious as to how
a normal computer graphics card would work. So, thanks for watching. If you like the video, learnt anything new
or want more feel free to subscribe, comment what you think down below, and subscribe for
new videos every single week. Also, feel free to check out previous tech
tips videos where you can learn some cool new stuff by clicking the links provided in
the description below. Once again, thanks for watching and I’ll
be seeing you in the next video.

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