LG PK990 (50PK990) Plasma HDTV Review

Time for LG's flagship 2010 Plasma offering!

by AVForums
TV Review

144

LG PK990 (50PK990) Plasma HDTV Review
SRP: £1,500.00

Introduction

The 50PK990 is a 50” Plasma display from LG's new INFINIA range. It's LG's flagship PDP model and features a new TruBlack filter, 1080p resolution, 4 HDMI inputs, THX Display Certification, and new for 2010, support for Freeview HD. At CES this year, LG were not shy about discussing the improved black level of this year's Plasma models. Since this was one of the biggest criticisms of previous ranges, let's see if the improvements make the 50PK990 a must-own HDTV.

Design & Connections

LG's 50PK990 is sleek and slim. The front of the display is entirely flat, as the TV uses the “one sheet of glass” design concept. There's really little else to add, because the styling is so effective and unobtrusive. It's a huge leap over the glossy black (or glossy black-blue) of the Pioneer KURO and Panasonic VIERA Plasma displays, which are prone to getting scratched with even the gentlest cleaning. The glass front on the LG's display will not suffer from this same fate.

The back of the TV features 3 HDMI inputs (the fourth is on the side), an RF input, Component video and stereo audio jacks, a single SCART input (good move, LG, save the space for more deserving interfaces), a PC input (VGA), and an RS232 port for system integrators. The side features a Composite video input, 2 USB ports, and the 4th HDMI connector.

Menus & Setup

In the typical LG tradition, the 50PK990's on screen menus are well designed, great to look at, and very user friendly. In the Picture Menu, the “Picture Mode” control lets you select a video preset. The high-quality modes are “THX Cinema”, “THX Cinema Bright Room”, “ISF Expert1” and “ISF Expert2”. The THX modes attempt to hit industry standards for white point and colour and are great for users who don't want to pay for the best possible quality via calibration, but are happy to get a close-enough preset. The “THX Bright Room” mode adjusts image parameters to combat ambient light in bright rooms (as the name suggests), whilst still adhering to mastering standards. The THX modes are somewhat restrictive on this display, in that all of the video controls are greyed out when they're enabled – even the basic controls such as Brightness and Contrast. In theory, this isn't a good idea because these may need small adjustments across devices, but with today's digital video outputs, such tweaks are often not necessary.

The two ISF modes unlock all of the picture controls which are disabled in the THX Mode. This includes the basic adjustments as well as the “Expert Control” menu. The Expert Control menu gives control over a wide range of video options. The most relevant ones are for Gamma (Low/Medium/High), Film Mode (film cadence detection for SD signals), and “Expert Pattern”, which draws TV-generated test patterns on the screen to allow you to set the controls if there are no suitable test patterns to hand (this is especially useful for the TV's tuner, since there is currently no channel, at least not on terrestrial TV, which routinely broadcasts test patterns). This menu also features Greyscale calibration controls (in regular 2-point as well as highly accurate 20-point modes!) and a 2D Colour Management system.


Features

LG's TVs have traditionally been jam-packed full of value-added features, and the PK990 is no exception. LG's NetCast feature is somewhat like Panasonic's “VIERA CAST” portal, and brings selected web content to your TV screen (YouTube, Picasa, and AccuWeather). Unfortunately, while accessing these features, the TV is locked in a very unappealing picture mode, which makes compressed YouTube videos look even worse than they should. It also forces sharpening and a high (blue tinted) colour temperature over Picasa pictures, so this feature is much less useful than it could have been.

Fortunately, the same restriction doesn't apply to photos viewed over the USB input from a memory card reader or a thumb drive; and as a result, high-res images viewed in this way can look absolutely gorgeous on the big screen.

Bluetooth connectivity is supported, as usual, but personally I've yet to find a compelling use for this. It's also worth reminding readers here that the 50PK990 has a Freeview HD tuner built in, so users can enjoy HDTV over an aerial for no additional monthly fee.

Test Results

Since the 50PK990 features a THX Cinema mode, I measured its Greyscale and Colour characteristics to see how well it would serve customers who don't want to have a calibration performed on their display.

Overall, the results were excellent for a preset mode, with most errors measuring under 2, making them almost unnoticeable. Correlated colour temperature hovered at around 6,000K in darker areas of the picture (making them appear very slightly too reddish) but closer to 6,500K in brighter parts.

Colour was great overall, with all primaries and secondaries measuring acceptably close to their targets. Blue appeared slightly biased towards Cyan and Yellow was slightly off-hue, but the THX mode still checks all the right boxes for largely satisfying, realistic colour reproduction. Let's see how we can improve upon this out-of-the-box result with a full calibration...

Since LG's higher end displays now offer 20-point Greyscale calibration control, I made use of this to dial in each intensity as close to perfection as possible. Most displays only offer control over “Low end” and “High end” areas, meaning that any errors must be balanced out across the range, but 20-point control means that every stimulus from 0-100 can be controlled with outstanding granularity (each stimulus can be independently selected in steps of 5%, so you can alter the Greysale at 0 IRE, 5 IRE, 10 IRE, 15 IRE, etc.) You can see the end results of this level of control for yourself in the above “RGB Color Balance” chart – errors are essentially non-existent. Reference quality Greyscale tracking? Yes. (Note: the 5% bias of blue seen at the “10” position is the result of the difficulty of measuring darker areas, and does not indicate an on-screen issue).

Colour was less spectacular, but still an improvement on the highly serviceable THX mode. The TV's 2D CMS features “Colour” and “Tint” controls for all six primary and secondary colours; the “Colour” control affecting saturation and luminance together. Using these controls, it was possible to rectify all errors except for the slightly off-hue blue. This represents overall Excellent performance that will satisfy all but the staunchest videophiles.

Video Processing

While running the video processing tests on the 50PK990, the first thing I noticed was that even with an unscaled 1080p signal, there was some degree of ringing around fine details in the picture (this is even with the “Edge Enhancement” control turned off). Sadly, this is an almost entirely undefeatable problem with the LG 50PK990 that no amount of adjusting could cure: the TV's video processor applies some sort of sharpening to the image at all times. Reducing the Sharpness controls only blurred the already sharpened image rather than removing halos, like a correctly implemented control would.

There is one way to sidestep the sharpening, but it only works for certain types of signal. If you label the HDMI input you're feeding the TV with as “PC” and the input signal type is 1080p at 60hz, the TV will enter PC Mode and you'll be free from the ugly ringing. Unfortunately, you will also lose the effects of the Colour Management system, and of course, this won't work with European HDTV sources, because those are 50hz-based and the PC mode will only enable if the signal is 60hz. This also means that you cannot avoid the ringing if your Blu-ray Disc player is outputting 24p. This is not the first time that LG have introduced such a scenario: certain models from 2008 had different issues that disappeared in the PC mode. (Interestingly, the Sharpening is only applied to the Luminance portion of the picture; the Colour channels are left completely untouched).

Moving on, I tested how well the TV smoothed jaggies in interlaced material. The 50PK990 did a good job here, with all three of the rotating bars in the HQV test pattern appearing smooth, except at the edges, which is quite common. In real world usage, there were no unusually obvious problems with jaggedness. Unfortunately, the deinterlacing circuitry did not engage Film Mode during the PAL 2-2 Film test on the HQV test disc, which means that film-based content (such as high-budget dramas and, of course, films) will lose a little bit of vertical detail. For the US NTSC TV system, the 3-2 test passed, which is good news for owners of older (non-upconverting) DVD players and large US DVD collections.

Finally, the scaling (the actual resizing of the SD image to HD) did not throw away fine details. However, because the TV applies Sharpening to all signals unless it's in the PC Mode, it was hard to judge the quality of the scaling due to the added ringing.

Gaming Performance

Under normal conditions, input lag on the LG 50PK990 measured at around 60ms, which is unusually high for a Plasma display. Sadly, enabling the “PC” mode did not manage to cut this figure down. Even with this lag, though, the experience of playing games on a large-screen TV is a good one, and the perception of processing lag varies with the individual.

Energy Consumption

After calibration, the following power readings were taken from the LG 50PK990:
0 IRE (Black screen): 150 watts
50 IRE (Grey screen): 290 watts
100 IRE (White screen): 348 watts

Picture Quality

One of the key advantages of LG's new PDP displays (when compared to last year's models) is the deeper black level that they are capable of producing. LG's promotional material gives the impression that this is due to a screen coating which attempts to reduce the effects of ambient light on the picture. However, the black levels are visibly better than previous models even in a fully dark room, so the improvements would not appear to be restricted to a screen filter.

One thing that isn't improved from previous LG PDPs, though, is image retention. During the review period, the 50PK990 would often suffer from visible retention even if the video causing it was only displayed for a short period of time (10 seconds or so). Image retention is where static on-screen images such as TV station logos or video game score counters leave shadows of themselves on the screen, even if they are no longer present in the video signal. Fortunately, none of the retention I encountered stuck around for too long, and cleaned up quickly after using LG's own “White Wash” pattern.

Overall, calibrated images look pleasing, but perceived detail takes a hit due to the additional Sharpening that LG have seen fit to include behind the scenes. Given the large size of this display, if this issue bothers you, then you would have to sit some distance back to avoid noticing the artefacts it introduces, which is hardly ideal. Test patterns are good for showing off this issue, but if you want a clearer indication of the effects of this processing, then here's a comparison showing something readers will be very familiar with – a web browser showing AVForums.com on the LG 50PK990. The image on the right shows it as rendered by this TV, whereas the image on the left shows what it would look like unprocessed. As you can see, the finest details that characterise the very best HD images (or in this case, make the text more readable) become smudged as a result of the processing.



On the plus side, the colour reproduction is excellent despite some very minor chromaticity errors (as illustrated on the triangular CIE charts earlier in this review), and the Greyscale tracking is essentially perfect. These two traits mean that images on the LG 50PK990 can still look very realistic.

Verdict

7
AVForumsSCORE
OUT OF
10

Pros

  • THX mode produces great Greyscale and Colour with the click of a button
  • One of few TVs currently on the market with a Freeview HD tuner
  • 20-point Greyscale calibration results in Reference quality Greyscale tracking
  • Less panel generated noise than several other Plasma displays

Cons

  • Image processing reduces the clarity of small details in the picture, which is counter-productive, especially on a High Definition TV
  • Image retention is still an issue
  • Input lag higher than several other Plasma displays
  • YouTube and Picasa photo viewing quality is lowered since the calibrated picture settings can't be used
  • Film Mode detection is not very robust; be sure to bring your own upscaling DVD player!

LG PK990 (50PK990) Plasma HDTV Review

LG's flagship 2010 Plasma model carries over the usual comprehensive calibration controls from previous ranges, and also brings a much needed improvement to black level, which makes on-screen images, especially in dark scenes, more satisfying than previous models.

Unfortunately, image retention is still an irritating issue, and intrusive video processing, while not entirely devastating, is completely unnecessary, especially on what is supposed to be a flagship model. Beyond these quirks, there's enough to like: colour accuracy is excellent, and the 20-point Greyscale calibration control brings Reference quality performance in this area. The THX mode also allows users who don't want to pay for calibration to see video quality that's nearly as good.

The biggest problem for LG, though, is that little of these strengths are unique to them any more. In the past, LG's calibration controls set them apart, especially from one other major Plasma manufacturer, but the competition has now caught up and has even outdone LG in the colour accuracy stakes. (LG's 20-point Greyscale calibration control is still a unique feature, though).

Ultimately, like so many things, your buying decision will come down to price. At around £1500, the 50PK990 is around £100-200 more expensive than Panasonic's mid-range TX-P50G20, which is a better display in just about every regard. Were LG's display to be cheaper, it would qualify for a recommendation based on its favourable attributes, but the truth is that there's at least one better display out there that can be had for less money - and thanks to LG's insistence on tampering with video signals, which does them absolutely no favours at all, there's likely to be more still to come.

Scores

Contrast/Dynamic Range/Black Level

.
.
.
7

Screen Uniformity

.
.
.
7

Colour Accuracy

.
.
8

Greyscale Accuracy

.
9

Video Processing

.
.
.
7

Picture Quality

.
.
.
7

Sound Quality

.
.
.
7

Smart Features

.
.
.
7

Build Quality

.
.
.
7

Ease Of Use

.
.
8

Value for Money

.
.
.
.
.
5

Verdict

.
.
.
7
7
AVForumsSCORE
OUT OF
10

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