Thursday, 20 June 2013

Pixels and Voxels

It was only recently that I actually looked at my computer screen. Until then, it was only what was displayed on the screen that concerned me. But then some questions popped up in my head.

How does the computer display such a vivid range of color?
How is the information about the color stored in the computer?
How does the computer make sense of the information stored?
What does the graphics adapter do in newer computers and why is it necessary?

This is my research in brief. You can get more information if you google the keywords that I've mentioned below

Computer monitors is by far the most important output device. Gone are the days when computers spew out a rolls of output on paper. The most important element of computer display is the pixel short for picture element. When you peer closely at your computer screen, you'll notice that its made up of tiny squares, these are the picture elements. Each pixel emanates a color.

Every color are composed of three primary colors: Red, Green, and Blue. What I mean by this is that the cells in the human retina is capable of detecting 3 colors. The brain takes the signals from the retina which is basically a function of the intensity of the three components and determines the color.
Therefore when R, G and B are combined in different ratios, other colors, secondary colors are produced.

Color Depth:  There is inherent ambiguity in the definition of the color depth. It is EITHER the number of bits used to represent each color OR the number of bits to represent each COMPONENT. The component refers to R, G, B. Obviously the first definition restricts the number of colors that can be represented as opposed to the first.

The problem of storing and displaying colors on a computer screen translates to an effective  method of representing the intensities of R, G, and B. Computers rely on using a particular bit pattern for each color intensity. Older computers used 8 bit color schemes, which means that 8 bits are used to represent a color. This allows for 256 colors and no more. Modern computers use 24 bits to represent colors(True Color), eight bits for each of the components, this scheme can represent about 16.7 million colors. Some computers use more than 24 bits, but they are uncommon. Printing also uses 24 bit scheme. 

Translating the Bit Pattern into Color

Now that we've figured out a unique representation for every color, how does the computer determine which color to display. The answer to this lies in the color lookup table (CLUT). The display devices have been designed to look into  this table to understand the definition of the binary values. Read the wiki here.

The range of colors that can be represented depends on the color gamut. It is fairly mathematical and quite complex to understand so I exclude an explanation here.

I then stumbled on Volumetric Pixels or Voxels!

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