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by Dinesh Thakur

VGA, which stands for video graphics array, is currently the most popular standard for PC screen display equipment. Technically, a VGA is a type of video adapter (circuitry in the computer that controls the screen). IBM developed the VGA for its PS/2 line of computers (the name "Video Graphics Array" is an IBM trademark), but loads of other manufacturers make VGA add-in boards (that plug into a slot in the pc) and VGA chips (in some pcs, these VGA chips are built right into the main part of the computer, the motherboard). A VGA monitor is a monitor that works with a VGA adapter.



 
by Dinesh Thakur

Vector graphics are stored in the computer as a set of mathematical formulas describing the shapes that make up each image. When you display a vector graphic on the screen or print it, these formulas are converted into the patterns of dots you can see. Because the dots are not specified unit! you display or print the graphic, you can change the size of the image without any loss of quality, and the image will always appear at the highest resolution of whatever screen or printer you're using. The term vector graphics means exactly the same thing as object-oriented (or just object) graphics.



 
by Dinesh Thakur

Multiscan refers to a type of computer monitor that automatically matches the synchronizing signals sent from the computer's video adapter (the video circuitry). On a standard television-type monitor, the image you see is formed by a single beam of electrons scanning lickety-split across the picture tube. The beam starts at one corner, traces a narrow horizontal line, then moves down a bit and traces the next line. The speed with which the beam travels horizontally and vertically (the horizontal and vertical "scan frequencies"), must match the synchronizing signals from the computer's video circuits.



 
by Dinesh Thakur

Monitor is another word for the computer screen. But "monitor" encompasses the whole piece of equipment, rather than just the screen part that you look at. You also might hear a monitor called a display, as in "Oooh, I got a new two-page display," or VDT(video display terminal), as in newspaper journalism, or CRT (cathode ray tube), which is the technical term for a picture tube. However, flat panel screens like LCDS are not referred to as monitors, even if they're housed externally from a computer.



 
by Dinesh Thakur

If an image is displayed on your screen or printed on the page in low-res (short for low resolution), that means you are seeing a low-grade quality. Some graphics are just low-resolution to begin with, such as graphics made in the paint file format at 72 dots per inch. Some graphics are created as complex, high-resolution images, but you may choose to display them on the screen or print them in low-res just to save time, since it takes longer for a screen or a printer to create the high- resolution version.



 
by Dinesh Thakur

LED stands for light emitting diode. You know those little lights on your computer, usually near the hard disk, that flash while the computer is working? Those are LEDs. They work on the principle of electroluminescence, which refers to substances that glow when you apply electricity. LEDs were used in digital watches, but now all digital watches use LCDs because LCD stakes less power.



 
by Dinesh Thakur

In a standard television-like computer monitor, an image is produced on the screen by a beam of electrons sweeping rapidly across the surface of the picture tube, lighting up the screen as it passes. Starting at the top, the beam traces one horizontal row across the screen, shifts down a bit and does another row, and so on, until the full height of the screen has been covered.



 
by Dinesh Thakur

The dot pitch of a color monitor measures the size of the tiny individual dots of phosphorescent material that coat the back side of the picture tube's face. The dot pitch helps determine how sharp the image looks, independent of the resolution (which is measured in pixels). A smaller dot pitch is better.

 
by Dinesh Thakur

CGA stands for color graphics adapter, the first IBM video card to permit graphics on the screen. We're lucky they've come out with better models, because CGA graphics are gawdawful crude. With a CGA, your screen can show up to 640 dots across by 200 dots up and down, with only one color. Even at that maximum resolution, pictures look really blocky and out of proportion. Pictures will look even more blocky if you want 4 colors on the screen at once, since you're then limited to 320 dots across and 200 down. If you can tolerate a totally chunky display of 160 by 200 dots, you can get a maximum of 16 colors on a CGA. Wow!

 
by Dinesh Thakur

LCD stands for liquid crystal display. Your digital watch uses an LCD to show you the time, and most portable computers use an LCD to display the screen. There is actually a liquid compound, liquid crystals, sandwiched between two grids of electrodes. The electrodes can selectively turn on the different cells or pixels in the grid to create the image you see.



 
by Dinesh Thakur

One of the basic and commonly used display devices is Cathode Ray Tube (CRT). A cathode ray tube is based on the simple concept that an electronic beam, when hits a phosphorescent surface, produces a beam of light (momentarily - though we later describe surfaces that produce light intensities lashing over a period of time).

 
by Dinesh Thakur

A pixel (short for picture element, using the common abbreviation "pix" for "picture") is one of the many tiny dots that make up the representation of a picture in a computer's memory. Each such information element is not really a dot, nor a square, but an abstract sample.



 
by Dinesh Thakur

Factors in determining refresh rates

A refresh rate is dependent upon a monitor's horizontal scanning frequency and the number of horizontal lines displayed.The horizontal scanning frequency is the number of times the electron beam sweeps one line and returns to the beginning of the next in one second. Horizontal scanning frequency is measured in kilohertz (kHz).

 
by Dinesh Thakur

Raster Scan methods have increasingly become the dominant technology since about 1975. These methods use the TV type raster scan. The growth in the use of such methods has been dependent on rapidly decreasing memory prices and on the availability of cheap scan generating hardware from the TV industry.



 
by Dinesh Thakur

There are used for erasable disks. MO system includes basic principles of both magnetic & optical storage systems. MO systems write magnetically & read optically. It has two standard forms : 5.25 inches & 3.5 inches.

 
by Dinesh Thakur

Plasma displays are bright, have a wide color gamut, and can be produced in fairly large sizes, up to 262 cm (103 inches) diagonally. They have a very low-luminance "dark-room" black level, creating a black some find more desirable for watching movies. The display panel is only about 6 cm (2½ inches) thick, while the total thickness, including electronics, is less than 10 cm (4 inches).

 
by Dinesh Thakur

In Shadow Mask CRT tiny holes in a metal plate separate the colored phosphors in the layer behind the front glass of the screen. The holes are placed in a manner ensuring that electrons from each of the tube's three cathode guns reach only the appropriately-colored phosphors on the display. All three beams pass through the same holes in the mask, but the angle of approach is different for each gun.

 
by Dinesh Thakur

This was one the earlier CRTs to produce color displays. Coating phosphors of different compounds can produce different colored pictures. But the basic problem of graphics is not to produce a picture of a predetermined color, but to produce color pictures, with the color characteristics chosen at run time.

 
by Dinesh Thakur

Conceptually the Direct View Storage Tube (DVST) behaves like a CRT with highly persistent phosphor. Pictures drawn on there will be seen for several minutes (40-50 minutes) before fading. It is similar to CRT as far as the electronic gun and phosphor-coated mechanisms are concerned. But instead of the electron beam directly writing the pictures on the phosphor coated CRT screen, the writing is done with the help of a fine-mesh wire grid.