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Philips Working on LCD TV Ghosting
agentfive writes "Philips is working on a new lamp technology to eliminate ghosting. Ghosting is a problem in LCD TVs when tiny pixels creating the image take time to switch on and off and can't do it fast enough. The problem, widely recognized as the main drawback of LCD TVs, is apparent in fast moving objects such as tennis balls, but even slower moving images get fuzzy. Philips will do something similiar to a Cathode Ray Tube (CRT) by switching the fluorescent backlight on and off at a rapid pace."
Isn't ghosting problem related to the speed at which crystals can reorient?
hilarious
I recently bought a 17" LCD monitor. It has excellent colour reproduction and I can't notice any ghosting even when playing FPS games. Is there any reason this same technology can't be used on LCD TVs without the need to make everything flicker? I can only guess that the cost is prohibative once you go beyond a certain screen size, but surely the larger pixel size of TV (as opposed to a high resolution monitor) would make fabrication easier.
Early LCD displays were bad, sure, but these days I use a CRT at work and a low-end 17" Advueu LCD display at home (on which I watch both TV and DVDs as well, in addition to gaming), and I can honestly say that the LCD's display quality--contrast, brightness, sharpness, lack of distortion--is far better than my Optiquest at work, and I haven't experienced anything even suggestive of a ghosting problem, whether while watching action films or playing FPS games.
STOP . AMERICA . NOW
Well but when will wew see TVs using OLED technology. For sure they will be alot better than LCD counterparts.
I must admit that I've never even noticed this problem with LCD screens. Maybe I'm just incredibly unobservant, but you'd think that something that's known as "the main drawback of LCD TVs" would be noticable to even the casual watcher.
:)
When I saw the title of this article, though, the first thing that came to mind was this old TV that belonged to a club at my highschool. It was hooked up to a little camera on a remote-control robotic camera mount that a former club member had created, so the idea was that people sitting in another room could swivel it about with a joystick. Unfortunately, the mount broke, so the camera (which then became known as buttcam, due to its lowered position) ended up stuck looking in the same direction for some long period of time. This background image eventually got burned in somehow, and it got to the point where people could walk in front of the camera and appear transluscent on the TV.... and the end result was something that deserved the name "ghosting" far more than anything an LCD TV can do
I'd rather deal with ghosting than have to go back to the days of CRT eyestrain.
There are many reasons why CRTs cause eyestrain, and I'm not convinced flickering is one of them, especially today when most screens can refresh at 85Hz at 1600x1200, and even higher at lower resolutions.
Another problem is the cathode ray tube which by design creates a static electric field on the screen. This field will first attract dust particles in the air, which are then charged with the same polarity as the screen and as a result, they are shot from it, directly at the viewer, something which causes dry eyes. LCDs do not suffer from this problem.
Another problem of the CRT are the analog pixels, which are not perfectly sharp. They are smeared, because the graphics card cannot make abrupt enough changes between colours, and the neighbouring pixels are further smeared as they travel along the VGA cable. (Becomes really noticable at high resolutions and high refresh rates. The signal is pushing the bandwidth limit of the cable). They are also smeared because the electron beam used to paint the pixels is slightly fuzzy. As CRT-screens age, they may increasingly loose focus. Depending on your type of CRT age/price), the image may be blurred further by coatings put on to reduce reflections.
Our vision really dislikes not being able to focus on things perfectly. It puts a strain on the small muscles used to contract the lense inside our eyes.
LCD-pixels are perfect rectangles and does not suffer from these problems as long as a digital interface is used.
Today CRT-screens are superior when it comes to color reproduction, dynamic range. They are also superior when displaying moving images, because of their strobing nature. These new strobing LCDs may change this, something I'm excited about.
A witty
Secondly, the image loses color definition due to the backlight's frequency not necessarily producing the same amount of light pure color. Some times red may be better, some times green. If it gets really bad the a color can be completely skiped. Depends on the addressing method of course.
Thirdly if the addressing method prevents the color definition from being an issue as multiple colors are being addressed at once lines may appear over time, or the screen may noticeably flash.
Lastly there is some attempt to increase the power of white while flashing. This can effect the chromaticity of the white (read colors making it up) and make it biased toward yellow (usually). The brightness can also bleed through the black and make the over all contrast ratio suffer.
Now if they got it to work properly, good for them. I'd just rather not get the first model with this tech if I were you.
I'd say more, but my guild is raiding.
LCD / DLP / CRT / PLASMA / ??? / ???? / ?????
I prefer LCD over everything else at the moment, including DLP. I don't like the effect of the pixel being switched on/off the produce a shade, where LCD can be varible (control wise) to produce variable shades.
I have owned several projects since 1997. I've never owned a CRT projector, however I like the color on the LCD ones by far. I notice the LCD's don't last as long as DLP. I am using them for entertainment purposes, I'm not doing power point.
Hey funny you mentioned that. I cannot stand anything less than 75Hz, and strongly prefer 85Hz or higher. I can actually see the difference as I switch from 60 to 75 to 85, 60 being outright painful. And yet when I get to fix or use some friend's computer, I often see that they are running it at 60Hz. After several attempts of trying to explain what is wrong with that picture, I just adapted a rule of surreptitiously changing the refresh rate while the owner is looking away. After all, if they are able to notice it, they can only thank me later.
actually your totally wrong. motion blur is when an object moves so fast our brains aren't able to disinquish it clearly. ghosting is the effect caused when a pixel changes colour slowly and you see a "ghost" image of whats moving. this effect happens on both crt's and lcd's, however it tends to be more pronounced on lcd's. just move your mouse around the screen quickly on your crt and you will see an example. you look like a right idiot now don't you!
If you mod me down, I will become more powerful than you can imagine....
The last time I saw this technology was at the 2004 SID (Society for Information Display) show, in Seattle. LG/Phillips had one in their booth. I believe they were using LEDs for the backlights and were cycling rows of them in time with the LCD update. Being 60 Hz, the flickering was noticable, but the ghosting was completely absent.
Here's the problem: With a TV or movie screen, the image is flashed very briefly (on a TV, different parts of the screen are flashed at different times, but that's not important), and your brain stitches the scene together. The hold time on the image is VERY brief, so while it looks like a steady picture, it's really a succession of flashes with relatively long periods of darkness in between then.
With an LCD, on the other hand, you could say that the hold time is as long as the frame period (16 milliseconds or whatever). The LCD has no periods of darkness. With the CRT and movie screen, your brain is what stitches the images together, inferring the motion. With the LCD, you actually see the image change, and your brain perceives that as a smear. IIRC, what's happening is that persistence of vision is working against you and you end up seeing two frames at once.
Besides, raster-scanning the backlight, there are two other things that can reduce the smearing effect. One is to increase the frame rate. The higher the frame rate, the smaller the motion steps. It essentially reduces the hold time on each frame.
At the show, I went to a seminar by a guy named Kompenhouwer. For any device, you can mathematically model how it converts its input to output. This is referred to as a "transfer function". This guy developed transfer functions for the LCD and for a CRT and inserted a filter (It was really precomputed in software, but you could do it in real-time) between the video signal and the LCD that applied the CRT transfer function and inverse LCD transfer function. Those together cancel out the smearing effects of the LCD and make it look more like a CRT. For static images, the filter does nothing, but as I recall, the effect of the filter on motion is to amplify the high-frequency components of the image in the direction of motion. I think that as long as you are tracking the motion of the moving image with your eye, it looks right, but if you don't, it looks weird (but I may be remembering that last bit incorrectly).
and they also don't have a "native" resolution crippling every other resolution that requires interpolation to display.
that and ghosting will never go away.
the best lcds have a 25ms response rate (not the bullshit 8, 12, 16 that manufacturers like to lie about) and that's not enough to get rid of ghosting. so they resort to tricks and say that the response rate is now 8ms.
lcds certainly have their place. lower power use, sharper (generally) displays, digital addressing, won't cause hernias for weak nerds/geeks, takes up little desk space.
but for people like me that can lift 22inch monitors and appreciates high end crts for gaming, i cannot make the switch to lcds. not to mention a high end lcd costs over twice as much as a high end crt.
so as the saying goes, the right tool for the job.
i'll continue to use crts for the foreseeable future. maybe OLED or some other technology can finally replace all the features that make crts great and have the benefits of lcds at the same time.
Science : Proprietary , Knowledge : Open Source
what would a "real 12ms" be? the fact of the matter is that the response of an lcd is too complicated to sum up in a single metric.
The latest lcd panel is 4ms and is in fact 4ms. Look at this graph produced by THG Showing the pixel intensity changing from 0 to 210 in 4.3ms but since the requested value was 175 they dont count it as 4.3ms instead they wait until the pixel is 178. Now the mfg figured out how to get the pixel to change in 4ms they are damn well going to slap 4ms on the box.
It's not a lie it's just a semantic. Tom's tells you that it is more important that the pixel be within 10% of the requested value before it should count as having changed at all - now that's a lie. Your eyes do not notice the pixel being 210 instead of 175 for 4ms, your eyes notice the complete and utter lack of ghosting.
bite my glorious golden ass.
if it were a real 12ms lcd, it would uniformly and under all conditions respond at least within that threshold.
So basically you just invent whatever nonsense you want to justify your unfounded beliefs. Alrighty then.
In the real world the VESA consortium set standards on how they would measure response times, with strict conditions under which it would be measured. Now I realize that you're an authoritative voice, but I think I'll trust the labs a bit more than I trust you. Anyone who has actually been involved with LCDs for the past 6 years or so would say that you're full of shit, given the vast improvements that have happened with LCDs.
they also lie (read deceive) about viewing angles of lcds. this one is much more well known among lcd afficionados
So basically one has to signup to the cult to get the "inside scoop", right?
It is interesting that LCDs have some real deficiencies that you totally ignored, such as a subpar dynamic range, and limited colour saturation and fidelity. Instead you go for some nonsense conspiracy theory balogna.
I can see the ghosting and I can see the flicker.
(CRT flicker and LCD ghosting) and I don't care.
This could be a problem for Philips for a lot of reasons.
People have a problem lumping an entire class of product together and "Once you've seen one duck you've seen all ducks".
I've seen it in Linux and SUVs.
Every Linux distro is diffrent and SUV is a class of vehical refering to many diffrent types of vehicals, Vans, MiniVans, Trucks, Jeeps etc.
But people think all SUVs are alike, all Linux distros are alike.
They also think all LCD TVs are alike. It's difficult to get most people to appreceate the diffrence in quality between a low end wide screen and a high res wide screen.
With LCDs people just think it's there. If you fix it by adding filcker people will get the idea that all LCDs flicker... and have ghosting. You'll have a hard time convencing anyone that there is a tradeoff.
Way back in the day I had a Sony Trinatron TV for a computer monitor. A friend noticed the guide wire and desided to ask me why do TVs have that.
My other computer uses a Zenith monitor (not TV) seeing that my Zenith didn't have the wire he concluded it was a diffrence between a TV set and a computer monitor.
It took me a while to get him to understand this was unique to the Trinatron.
Thankfully I had a Zenith TV in the living room for watching TV. Thow for the first 5 minuts he sware he could see the wire on it.
I don't actually exist.
Film is actually used because, historically, the electronic cameras and recorders sucked beyond belief. Resolution was crap. Media self-erased and wore quickly. Dynamic range was pitiful, and saturated highlights were sharply clipped and blown out. Noise was high. Occassionally you see electronic TV recordings from the '70s and the picture is butt ugly. Film may be expensive and cumbersome, but it has great resolution, great dynamic range, reasonably low noise, and lasts forever if stored properly. A true film-replacement electronic camera is still a laboratory curiosity and expensive as hell.
That's an important point. Migraine and eyestrain-induced-discomfort (which is probably mild migraine in many cases) depend on how and what you watch too. Computers use sharp, high-contrast content with repetitive patterns. The eye is constantly moving around in fast, jerky motions. There are incentives to constantly stare at the screen without breaks. This is very stimulating to the visual parts of the brain. (I'm typing this with the lights turned off, wearing sunglasses. Three guesses why.) Reducing flicker is one of the few ways to reduce the irritation.On the other hand, TV and movies have soft edges and low contrast, and the eye does not move much or rapidly. You can look away occassionally without feeling like you're missing something. So the designer can get away with a lot more flicker without pissing off viewers' brains.
Horrible writing to say the least - or - a terrible mis-understanding of how a CRT works. First off, CRT's don't have backlights as the statement seems to imply, and secondly, CRT's don't eliminate ghosting by turning anything on or off. It happens that the decay rate of the phosphor is such that when the electron beam re-scans the tube, the phosphor has exhausted its charge from the previous scan.
To get a 'similar' fix, they would have to flip the pixels faster - not interrupt the backlight, which is a completly different approach to fixing the problem than doing anything 'like' a CRT.