LCD TVs Brightness And Contrast
by: Eli Aloisi
Unlike computer monitors, brightness is an important parameter in the choice of a LCD TV set. Since a TV set is viewed from a distance, a (measured) brightness of 220 to 250 nits is appropriate, where for a computer monitor, that would be too bright. When we talk about brightness here, we're referring to the values we've measured ourselves, not the exaggerated, basically useless values claimed by the manufacturers. Some claim up to 800 nits of brightness, a level that would be like looking at a welding torch through a color slide.
Contrast is another story. A good contrast level is always preferable, but you have to be careful not to confuse contrast ratio and screen dynamics. Here's an example to make that a little more clear.
Here I am trying to display concentric circles in shades of gray, from the lightest to the darkest. Screen A shows the shades correctly, but screen B shows only two shades. They have the same contrast ratio - that is, the relation between the whitest point on the screen and the blackest - but not the same dynamics. Screen A shows more details and more nuances than screen B. So as you can see, you need to be careful about manufacturers' claims regarding contrast ratio.
Latency is a crucial parameter for users of LCD Televisions, because LCD panels are fundamentally slow. The latency measurement indicates the time it takes for a pixel to change from totally black to saturated white and back to totally black again. Unfortunately, that value is not very representative of reality, because pixels rarely make such extreme transitions. A pixel can change, for example, from dark gray to a lighter gray, and in that case the latency is much worse than what the manufacturers claim.
This curve shows the different latency values as a function of the gray level to be displayed. A change from black to white is shown on the curve as a point at 255 on the X-axis, a black-gray transition is 125 on the X-axis, an alternation between black and dark gray is 50, etc. The official ISO response time specified by the manufacturer is only for black/white transitions (0/255). While the value we measured is in agreement with the manufacturer on this point, it doesn't mean much as far as the panel's real-world responsiveness is concerned.
While computer applications are highly sensitive to latency, TV sets are a different matter. A TV doesn't have a refresh rate of 60Hz by default - depending on the format, the rate is most often 30 Hz, or 30 images per second interlaced. That would seem to mean that a latency of 33 ms (1/30 Hz) would be sufficient, but that's not so. It's theoretically sufficient for an interlaced signal, but not for applications on a PC, like video games for example. And with PC/TV convergence the coming thing, 33 ms is not really enough. It would also rule out progressive video formats like 720P. And even for ordinary TV use, a 33 ms latency would be visible when sudden movements occur on-screen.
About The Author
Eli Aloisi is one of the many knowledgable staff members that encompass the PlexHomeTheater.com community. For more great articles check out www.PlexHomeTheater.com.
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HDTV ? The High Resolution Television
HDTV ? The High Resolution Television
by: Gagandeep Dhaliwal
The expansion of hdtv is High-definition television. The hdtv means television signals broadcast with a higher resolution than traditional formats like NTSC, S?CAM, PAL. The hdtv is broadcasted digitally, except for early analog formats in Europe and Japan.
Historically, the term high-definition television was also used to refer to television standards developed in the 1930s to replace the early experimental systems, although, not so long afterwards, Philo T. Farnsworth, John Logie Baird and Vladimir Zworkin had each developed competing TV systems but resolution was not the issue that separated their substantially different technologies. It was patent interference lawsuits and deployment issues given the tumultuous financial climate of the late 20's and 30's. Most patents were expiring by the end of WW2 leaving the market wide open and no worldwide standard for television agreed upon....
HDTV ? The High Resolution Television
Lcd tv > HDTV ? The High Resolution Television
What are the Projection Television Technologies Available?
What are the Projection Television Technologies Available?
by: Bill Ransom
There are four types of rear-projection TV's available currently. These are the older CRT rear-projection, DLP rear-projection, LCD rear-projection and LCoS rear-projection. Most available today are HD ready and can display digital signals.
CRT Rear-projection : these are the projection TV's that have been on the market for years. CRT or Cathode Ray Tube technology is the same technology that your old TV set's used. There are three tubes in these projection TV's each for a primary color and they project the light onto the TV's screen. Since they require three CRT tubes these TV's are very big and deep. Most CRT projection TV's come in 50 inches or larger screen size. CRT rear-projection TV's are becoming extint and many companies do not make them anymore. They need to be adjusted frequently to keep the colors in line and the image quality and viewing angles are not as...
What are the Projection Television Technologies Available?
Lcd tv > What are the Projection Television Technologies Available?
Comparing Digital Camera Features
Comparing Digital Camera Features
by: Steve Gargin
More people are able to afford digital cameras because their prices are falling but the number of characteristics is rising so it is important to be able to compare digital camera features.
The first step in being able to compare digital camera features is to decide what you want to get out of your camera. If you compare digital camera prices you will see that for shooting family snapshots you can get a good basic digital camera for under $400, while a professional model is over $2,000. When you compare digital camera features you need to know the extent of the use you are going to get out of it.
It is essential when you compare digital camera options to understand the issues of image resolution, which is measured in megapixels. Basically, the more megapixels, the higher the resolutions of the final image but you definitely need to compare digital camera images with your actual requirements....
Comparing Digital Camera Features
Lcd tv > Comparing Digital Camera Features
Guide to Buying a Flat Screen TV
Guide to Buying a Flat Screen TV
by: Nathan James
If you?re ready to invest in one of the fabulous new flat screen televisions that everyone is talking about these days, there are some things you should know. There are several different types of flat screen technology, and it?s important you understand the pros and cons before you spend thousands of dollars on a TV.
Most people buy electronics as a long term investment, hoping their TV will last them for many years to come. By understanding the basics of flat screens you are much more likely to make a wise decision.
Plasma versus LCD
The two major types of options when it comes to buying a flat screen TV is plasma or LCD (liquid crystal display). Plasma televisions are more expensive than LCD televisions, but the vast difference in price seems to be getting smaller. However, if you?re looking for a massive flat screen TV, plasma is often your only option. The larger the LCD, the...
Guide to Buying a Flat Screen TV
Lcd tv > Guide to Buying a Flat Screen TV