December 2007
Monthly Archive
LCD TVs Brightness And Contrast
Posted by Admin on 31 Dec 2007 | Tagged as: LCD Televisions
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.
LCD Monitor vs CRT Measurements - What You Should Know Before You Buy
Posted by Admin on 30 Dec 2007 | Tagged as: Flat Panel LCD
LCD monitors are not the same size as CRT monitors. LCD monitors are actually larger for the same sized CRT monitor! Monitor measurements are measured diagonally. Since the advent of the television, this has been the industry standard for screen measurements. When computer monitors hit the scene, the measurement became the diagonal measurement of the tube itself, not the actual viewable screen. When you look at your monitor, there is a plastic box that houses your CRT tube and other components, but when you look at the front of your monitor, there is probably an inch or more of framework around your picture tube. This hides the rest of the CRT tube that is enclosed within the box.
Now take a ruler or tape measure, and measure the actual image you are viewing, measure diagonally, and you will see that the actual measurement is smaller than the monitors claimed size. For example, my 19 inch CRT monitor, measuring the actual image from the bottom left hand corner of the picture to the upper right hand corner is actually 17.25 inches, or in other words, only .25 inches larger than 17 inches, if the monitor measurement were the actual viewing screen this 19 inch monitor would only qualify as a 17 inch LCD monitor. This is where the LCD measurement comes in.
LCD monitors are measured by actual viewable area of the screen. They do not have a large rounded out tube beyond the screen, it is a flat panel of Liquid Crystals behind which are a series of tube lights that shine through the color crystals to illuminate your display. A 17 inch LCD monitor is 17 inches diagonally, a 19 inch monitor is 19 inches diagonal or about 1.75 inches larger than my example of the CRT tube.
Another little known glich in monitor measurements is how the diagonal measurement of a widescreen monitor reduces the overall height of the monitor which in turn reduces the actual size of a standard 4:3 to a smaller size. Example: If you purchase a 32 inch widescreen TV and watch a standard broadcast movie in it’s original format, you in essence are watching a 26 inch television. A more in depth look at how this measurement effects the full screen format, please read my Widescreen article.
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My name is Dan Dunkin, I have been working on computers, building and upgrading as well as programming computers since the first tandy Color computer came out in 1980. Originally I programmed in QBasic, later I explored OS9 which was basically a Pascal based language, then with the technology increases into the pentium chips I finally merged this into the Visual Basic fields. In dream shopping I’ve discovered where to find values for different types of electronics and like to share them with others through my website. |
FCC Threatens Decency Standards for Cable TV
Posted by Admin on 29 Dec 2007 | Tagged as: Plasma TV
At last, the Federal Communications Commission has reacted to the social damage of sex and violence by out- of-control cable and satellite television networks.
My dander was aroused by a sleazy cable program that I stumbled onto while surfing the boob tube. What I watched for five minutes was disgusting and alarming.
A baggy pants street gang - including two girls with bulging halters and peek-a-boo skirts - chased a young man.
They cornered him and beat him to the pavement. Then, while the boys pinned him down, the girls straddled the victim, hoisted their skirts, dropped their crotch covers and urinated into the victim’s face. Close up and in living color.
I cringe in describing the scene, but cable producers, advertisers and - presumably — cable viewers either enjoy sexual deviation and depravity, or have no moral compass.
We seem to be up to our chins in a sea of filth, murmuring, “Don’t make waves!” — while Howard Stearn, king of cable filth, cruises about in his speedboat.
On his tow cable, is the Internet email system open free to purveyors of pornography, cut-rate drugs, stock tips and Rolex watches. The wonderful Google information search engine also is sinking into the quagmire by featuring bloggers with idle time and a $399 computer.
Finally, on Tuesday, Federal Communications Commission Chairman Kevin J. Martin blew his whistle. At a congressional hearing, he warned cable and satellite providers. If they fail to promote family-friendly viewing, Congress could impose the same decency standards in effect for broadcasters.
Over-the-air television was brought to heel 40 years ago by government control of the limited spectrum of “public” broadcast channels. Technology since then has given us glass-fiber cables and Satellite transmitters with an unlimited number of channels.
Now we are in the situation lambasted 44 years ago by then FCC Chairman Newton Minnow. In a landmark speech titled “Vast Wasteland” — delivered to the National Association of Broadcasters — he excoriated them.
“I am here to uphold and protect the public interest,” he declared. “Some say the public interest is merely what interests the public. I disagree. When television is good, there is nothing better. But when television is bad, there is nothing worse!
“Why is television so bad? I have heard many answers - demands of advertisers, competition for ever-higher ratings, need to attract a mass audience, high cost of programs, insatiable appetite for programming material.
“However, I am not convinced that you have tried hard enough to solve them. I am not convinced that the people’s taste is as low as some of you assume.”
“I hope you will agree that ratings should have little influence where children are concerned. It used to be said that there were three great influences on a child - home, school and church. Today, there is a fourth great influence, and [broadcasters] control it.”
The “Vast Wasteland” speech — and threat of denying access to publicly owned broadcast frequencies — persuaded television networks to clean up their acts in general and relegate raunchy stuff after 10 p.m.
Even so, some prime-time comedies step over the decency line. They seem infatuated with double entendre wise cracks, copulation and toilets.
Chairman Martin offers some simple solutions:
* Sell only those channels purchased a la carte,
* Offer family-friendly program packages,
* Government limits on indecency and violence.
How about all of the above?
The House of Representatives has passed a bill that would raise the indecency fine on cable/satellite companies to $500,000 from $32,500 — as is in effect for broadcasters. The bill languishes in the Senate.
Ultimate answer to depravity and violence in the market place is societal norms. Yet, society will collapse if we continue down the road of “anything goes” - per ancient Rome.
Sadly we grow too soon old, and too late smart.
PARTING SHOTS
California Congressman Duke Cunningham resigned after admitting he took $2.4 million in bribes. He will give back $1.8 million and faces 10 years in prison. However, he keeps his congressional pension of $60,000 a year. Is this a great country, or what?
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People who do not worry about politics should have their television set repaired.
Lindsey Williams is a Sun columnist who can be contacted at:
Website: http://www.lindseywilliams.org