|Understanding Video Terms|
|Home Theater Feature Articles Video Related Articles|
|Written by Mike Levy|
|Thursday, 01 September 2005|
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AV Education on RHT
Understanding Video Terms
Written by Mike Levy
The world of audio and home theater is littered with often confusing terms that get tossed around freely by salespeople and writers. Nowhere is that more prevalent than in the world of video. You may have seen some of these terms on the menus of your bigscreen TV, but rarely are they ever defined. As an ongoing feature, we plan to help shed some light on the dark world of video terms. As you will see, they aren’t too confusing after all.
Screens • Video Maladies
eneral Video Terms
• Contrast is the difference in brightness between dark and light parts of the screen.
• Contrast Ratio is measured by comparing the brightest white to the darkest black available on a screen. This is not the same as the contrast control, which alters the level of white on the screen.
• Brightness is the absolute light output of a screen. This should not be confused with the brightness control, which adjusts the level of black on a screen.
• Tint is color balance. Most tint controls allow you to adjust the red/blue levels.
• Black Level is the darkest black on the screen; it can be altered by the brightness controls.
• Absolute Black is the level of black when all lights are off and the power is off.
• Gray Scale is the reproduction of various levels of light output. A well-defined gray scale will have many levels of gray from black to white and look continuous.
• RGB simply stands for Red, Green and Blue, the primary colors of the video world. An RGB connection sends each color separately.
ypes of Video Displays
• CRT Stands for Cathode Ray Tube, utilized by the ancient old-style vacuum tube TVs.
• DLP stands for Digital Light Processing, and is a proprietary name for the micro-mirror imaging chips made by Texas Instruments.
• D-ILA Stands for Digital Image Light Amplification and is a proprietary name for the JVC version of reflective LCD panels.
• LCOS stands for Liquid Crystal Oxides on Silicon, which is another method of creating reflective LCD projectors.
• Plasma is a gas of ionized particles, used in flat panel sets to create light.
• LCD stands for Liquid Crystal Display. Polarized liquid crystals of Silicon are electro-statically controlled to variably block light and create an image.
• Big Screen is a much-maligned term. Anything over 32 inches is considered a big screen, but in my mind, a big screen is one that is so large it dominates the room it is in. Rear-projection TVs are often called big screens at retailers.
• Analog Projector is the old-school, three-tube CRT type of video projectors.
• Digital Projector is any projector that cuts the picture up into individually accessed pixels. All digital projectors presently use an imaging chip and a bulb.