FAQ: LCD versus Plasma

[Richard]

Updated 03/07/2010

Viewing Angle
Plasma: Not an issue.
LCD: Depends on how much you pay.

Most inexpensive LCD will have problems and the effect is the color and brightness changes. Paying more gets you into a different panel design that may have no problem or limited viewing angle problems. The catch here is inspect what you expect! Go to the store to confirm the LCD you have interest in does not have this problem in your application. Another element to watch out for is horizontal versus vertical viewing angle. Some may do well with the former but suffer far more from the latter. Mounting over the fireplace is a perfect example of application; in this case vertical viewing angle will be just as important as horizontal unless you buy a mount that allows you to point the display downward if you find that acceptable. In general most of the upper teir LCD product has this licked but product is not at a point where I can say you should expect excellent results from every manufacturers top tier. At this time you still need to inspect what you expect.

Power Consumption
Plasma: The most power hungry display currently available.
LCD: Significantly less and in about 3 years even less again.

LED driven LCD consumes less power creating less heat than it’s florescent counterpart. The power savings to individuals is not much more than $30-50 per year, per display.

Heat and Ventilation
Plasma: Runs hotter than LCD but not by much
LCD: While less than plasma it still puts it out.

With either technology you should provide ample airflow if you are going to put the product into an enclosure. Failure to do so could void your warranty. Out in the open on the stand is not an issue but you may notice your room is a tad warmer.

LED driven LCD consumes less power creating less heat than it’s florescent counterpart.

Glare
Plasma: Lots of glare; after all it is a piece of shiny glass.
LCD: for 2010 over half of the available products now have shiny screens too

Many have applied glare reduction to the screen and while helpful it can’t come close to LCD product. Unfortunately with the recent change it is more difficult to find an LCD with an anti-glare screen

If your room has a lot of windows you may have already noticed glare on your old analog CRT that also has a shiny glass screen. An LCD sporting an anti-glare screen would fare better in that application.

Blacks
Plasma: A wee bit blacker than LCD
LCD: Deep blacks as well

Both technologies have made dramatic improvements in this area of performance. For LCD beware of inexpensive product if black performance is important to you. While top tier plasma may have a slight advantage you would need to use the product in a completely darkened room to get any real benefit.

Burn-in or Image Retention
Plasma: Still susceptible regardless of all the marketing hype stating otherwise
LCD: Does not burn but can suffer image retention which you could easily recover from.

Plasma has made improvements using more resilient phosphors along with supporting tools like orbiting to reduce this but it still cannot withstand hours upon hours of black side bars or tickers common with news and sports channels. While burn-in and image retention are considered one and the same due to phosphor based displays where the phosphor coating itself is wearing down for LCD burn in does not exist and the only term that applies is image retention. Each pixel of an LCD display is made up of crystals that change their direction to either block light or allow it to pass through. For LCD you get image retention when the crystals have lost their range of motion, they are stuck. Both technologies can use specifically designed patterns to remove image retention and for some these tools are part of the product in the customer menu. For plasma you are wearing down the surrounding phosphors to try and get them to match. For LCD you are trying to force the crystals to go from one extreme to other to recapture the full range of motion.

If you are the type of viewer that wants every inch of the screen to have an image, you hate black bars in any shape or form, then the majority of burn in issues with plasma are of no concern since you will be using aspect / format settings to fill out your screen.

If you are the type of viewer that prefers correct geometry, seeing all of the image and black bars are just fine then LCD is preferred. SD 4:3 content will remain with us for a very long time still and plasma and black side bars are a good recipe for burn in disaster.

Black bars top and bottom are of little concern because those come from movies and there is enough of a mix with movies along with HDTV content to dramatically reduce such concern. Station logos and news ticker tapes on the bottom are the most common form of burn in and plasma owners need to be very wary of them.

Transportation
Plasma: The most fragile and heaviest product.
LCD: significantly lighter and fairly resilient but take extra caution with the screen

Plasma is a sheet of glass and should be transported just like a sheet of glass; on it’s side standing up slightly leaning against a solid surface and secured. Do not lay the product down flat on it’s face or back for transportation. Unlike plasma, LCD allows a certain degree of flexibility from the screen down to the glass CCF backlighting tubes and LED takes the CCF tubes out of the picture. This product can be laid face down on a flat surface provided the support is on the frame surrounding the screen or on it’s back. With LCD the main concern is preventing an impact into the screen or excessive pressure pushing the screen in.

Both can suffer screen damage without any external evidence that this has occurred and will not be discovered until the product is powered up or repaired. Plasma uses plasma gas and if the screen is cracked the gas will escape and there will be no image. Plasma can also suffer from screen damage that causes bars or lines on the screen. For LCD, once the back light is working, you will clearly see the crack and the spiderweb of colored lines surrounding it. This is no small issue for the service industry for products being shipped by national carriers or consumers carrying in the product. Just recently there was an exchange amongst NESDA servicers to create the language for a document that the customer signs removing all liability for damaged screens from the service center when a product is turned in for service having a problem which does not allow an image to be seen to confirm the panel is intact.

Performance Related to Video Standards
For professional applications LCD angular viewing remains a problem. While the improvement may be more than acceptable for the mass market, maintaining calibrated color temperature requires the viewer always remain in the middle of the screen (CRT RP was no different).

LCD actually does a better job of meeting the numbers than plasma. A dirty little secret of plasma for years now is that it uses dynamic gamma to either compensate for a power supply that can’t keep up with demand or recently, with the green requirements, to reduce power consumption. This means bright dynamic pictures will be rendered correctly with LCD but with plasma those same images will look flat, less dynamic, and in brighter areas the wrong shade of color. The degree of error will be a moving target directly related to picture content. Without them being side by side for comparison most will not notice this attribute of imaging yet if you are seeking performance that meets video standards this is one important area plasma has a problem with.

When motion is added to the image plasma can have an advantage in detail resolution. Studies have been commissioned to prove this imaging anomaly using special equipment and specific procedures (far too difficult to simply measure by eye using test patterns) to the benefit of marketing plasma over LCD. I can’t say that anyone has directly noticed this flaw with LCD when viewing actual content along with the fact that all displays suffer from this to some degree. Indeed, those documenting and reporting the flaw are plasma manufacturers. Widescreen Review published an article from Dr. Soneira of DisplayMate Technologies comparing plasma to LCD and motion blur was one of the leading topics. His conclusion is that while LCD may fail laboratory motion tests, imaging professionals are unable to detect any visible difference with actual video content.

LCD does suffer more than other displays with motion strobing directly related to 24 and 30 frame content due to the very high dynamic range and contrast ratio the technology offers. All displays suffer from this to some degree right down to your local movie theater showing the original film. For LCD this is what 120hz and 240hz processing is trying to eliminate. As of this time most imaging professionals agree that while this video processing does remove the artifact it also destroys natural image fidelity. For a deeper discussion please refer to the following two articles.

Waveform 09A Motion Blur and 120hz LCD Frame Rate Processing
LCD Specs Playing with Your Eyes

LCD pixel speed has been a major concern in years past yet at this time this concern should be reserved for inexpensive LCD product. Using the example of a baseball going across the screen you will see a trail of ghost baseballs lagging behind it when pixel speed is too slow. Beware of noise reduction circuits used to make SD content more acceptable can create the same effect when viewing a product in a store that does not provide any HD content for the displays; that has nothing to do with pixel speed.

Inexpensive LCD does not have proper color saturation due to the generic CCF backlighting used for over a decade and this is well known by imaging professionals. You may note the richer color of other display technologies compared to inexpensive LCD product near by in your local store. To get an LCD to have the correct color response of other display technologies requires the backlight be WCG-CCF, or wide color gain cold cathode florescent. Unfortunately this year I have started to see manufacturers failing to differentiate standard CCF from WCG-CCF in their specifications on the internet which means you might need to find a quality review that looks for such things to find out if the CCF model you are interested in is WCG. LED is the new backlighting kid on the block for LCD. While it is color correct like WCG, manufacturers have added a new feature that can change the LED light output at the pixel level or in smaller sections of the screen to extend dynamic range; make peak white brighter and peak black darker. At this time the jury is still out on whether this is merely another sales tool of magical marketing hype and viewer perception that corrupts video standards versus a process that provides a real benefit while maintaining video standards.

More Links
720p versus 1080p
Selecting the right picture aspect/format for 1:1 pixel mapping