Black Level
We always remind readers not to expect top-class black-level performance from IPS LCD TVs… although they get nearly everything else right (at least compared to the LCD competition), contrast performance is not this LCD type’s strong point. Such is the case with the LG 42LM660T: with the [Backlight] control set so that a full white screen measures at our target of 120 cd/m2, black measures as being 0.155 cd/m2. That’s basically the same as other recent IPS displays such as the Panasonic TX-L42ET50, but these blacks are greyer compared to VA-type LCDs (as an example, Samsung’s UE40ES7000 managed 0.05 cd/m2) and are in a totally different category to the best plasma televisions (Panasonic TX-P42ST50’s 0.009 cd/m2).
Many users will probably want to enable the [LED Local Dimming] feature as a compromise. This will cause the TV to vary the brightness of its LED light sources in relation to the brightness level of the video. This does of course mean that any brighter details during these dark scenes will be harder to see, and the overall image will be duller – unlike a plasma television, or to a lesser extent, a fully LED backlit local-dimming LCD, you can’t have it both ways with pure white and jet black objects existing in the same screen. To their credit, LG affords the user full control over this, with Low, Medium and High settings, as well as an Off switch.
Of course, for the less-than-optimal black level reproduction of IPS LCD panel to be an issue, you’ll need to be watching in a dim to dark environment. If you’re installing the LG 42LM660T in a brighter room, and are predominantly watching during the daytime, you’ll likely have no complaints.
Motion Resolution
The LG LM660T eeks out 300 lines of motion from the FPD Benchmark Disc’s horizontally scrolling test, which is on the low end of the scale (interpolating LCDs and plasma displays manage 900-1080 lines). Some white ghost edges also surround the black portions during the scroll (these are LCD panel overdrive errors, called “inverse ghosting”). In its category (non-100hz/200hz LCDs), this is actually some of the better performance we’ve seen. Naturally it’s behind Plasma and 100hz/200hz LCDs, so don’t expect high motion video content (like football games with fast camera pans) to appear free of motion blur.
However, the baseline LCD motion resolution of 300 lines is enough to show low motion content (such as 24fps film) without visible motion blur, and here the 42LM660T does a very servicable job. Beyond the very mild and rare inverse ghosting we mentioned, there are no additional motion artefacts, such as the black trails (which are quite common with VA-type LCDs).
One last point to mention is the [TruMotion] control present in the 42LM660. Engaging this option at any of its settings (other than “Off”, obviously) will cause the TV to generate new intermediate frames, and will smooth motion, producing what has become known as the “soap opera effect” with film content. On LCD TVs, this feature is often bundled together with motion resolution benefits. However, the LG 42LM660T does not feature a 100hz/200hz panel, so turning on [TruMotion] will only introduce motion smoothing without any benefit to motion resolution.
High Definition
We’re very happy with the image quality from the LM660, for the simple reason that it can be configured to produce an accurate, unadulterated image with minimal effort. Even before calibration, with a slight red tint, the 42LM660T’s images were rich and engaging in the “ISF Expert” modes. After calibration, accuracy naturally improved to a basically perfect level. There is no forced edge enhancement, and unlike some higher end LG and Samsung HDTVs we’ve reviewed, no forced noise reduction, allowing for as much motion details as the panel can show to be reproduced. The LCD panel in the 42LM660 is operating to its full, with any limitations down to the panel used, rather than to human error. In other words, LG’s engineers have done an excellent job making a flat-screen television out of the parts they’ve been given, so thumbs up.
Films like Drive (shot on the digital Arri Alexa) came across brilliantly on the LG 42LM660T. The lack of any forced noise reduction allowed the gentle noise from the camera’s CMOS sensor (which doesn’t look too different to very light film grain) to come through untouched, adding a touch of extra perceived detail to the already very rich image. Night shots were, as we expected, compromised slightly by the panel’s less-than-ideal black level, but the effect wasn’t hugely damaging, and at least there was very little in the way of “clouding” to dirty up night scenes.
As we already mentioned, black levels are not the strong point of IPS LCD technology: blacks appeared with the usual grey “LCD mist” that we commonly see with these panels, and the effect accentuates the more the user sits off-centre. However, in daylight, the LM660T’s images appeared rich, naturally coloured, and vibrant, barely being hobbled by the IPS panel’s lighter-than-ideal blacks. IPS’ viewing angle strengths are apparent, and although contrast performance diminishes slightly when the panel is viewed from the sides, greyscale, gamma and colour more or less stay put, which goes a long way in presenting a not-too-compromised off-axis image. This compares favourably to VA LCD panels, which often become somewhat greyer and present a purpleish or pink tint, with unnatural gamma characteristics (such as accentuated mid-tones but crushed highlights), when viewed off-axis.
3D Material
The LG 42LM660 implements the company’s passive 3D technology (which their marketing department cleverly called “Cinema 3D”). The one Achilles’ heel of this system is the fact that it produces the lowest resolution 3-dimensional image on the market, although users won’t see this in the form of a blurry picture, because the image has dark lines visible over it when viewed through the polarized lenses on the 3D eyewear. With passive 3D, as it is implemented in televisions, half of the lines on screen are dedicated to the left eye image, with the other half being dedicated to the right – the glasses make sure the correct lines are blocked from the eyes in which they don’t belong.
That isn’t the only resolution limitation that the 42LM660T has: there are limitations on the video processor side, too. First, we fed it our 3D Side-By-Side test pattern, and noticed that the entire image was pixellated in both the horizontal and vertical directions. Even before we put on the glasses, we could see that the vertical resolution was being halved, with the discrete black and grey lines in our test chart appearing in the 3D mode as a solid grey block. We imagine that this has been done to blur out fine details and prevent aliasing (jaggedness) being visible, which could happen if unfiltered sharp edges interacted with the panel’s own resolution limit. The reason for the pixellated look, though, is less clear: it should be possible to apply a vertical softening to the image without introducing this as a side-effect. It appears there is some other limitation at work affecting the quality of the scaling with side-by-side content.
We had a look at Full HD 3D images from 3-D Blu-ray on the LG LM660T, and found that although the image is still vertically pre-filtered in a similar way as we described above, we couldn’t see any of the pixellation that affected the side-by-side test pattern. (We did find one bug where flattening the tri-dimensional image into 2D resulted in skipped frames and occasional juddery motion, so if you want to playback 3D movies in 2D, you should have your player do the conversion instead).
With that mentioned, the relative simplicity of the passive 3D system brings many other benefits to the extra-dimensional performance of the LG 42LM660: cheap, plentiful, lightweight glasses which produce a considerably brighter image with no flicker. With the sizeable issue of resolution aside, users can expect the same picture quality performance as in the 2D display mode, without anything in the way of additional motion judder or severe colour tints. The 42LM660T offers a more naturally coloured 3-D image (before 3D calibration – which let’s face it, is a niche service at the best of times) than nearly all active 3D TVs, although calibrating the latter technology redresses most of the balance, if you’re in the minority of having that option available to you. 3-D images had a good amount of depth, with very little crosstalk, provided we complied with the viewing angle requirements of the passive 3D display technology.
Standard Definition
SD processing on the LG LM660T is excellent, with the TV effortlessly scaling and deinterlacing standard-def signals, and portraying them in as good a light as possible. Diagonal interpolation is excellent, meaning video camera material is deinterlaced with minimal jaggedness, and the 42LM660T also detects common PAL and NTSC film transfer cadences correctly, presenting films stored in interlaced video carriers with no jaggies and full vertical resolution. Scaling is also excellent, presenting crisp standard-definition images with almost no ringing. Aliasing is almost non-existent; suggesting that a gentle anti-aliasing step is being used.
Console Gaming
There are a couple of ways to cut input lag down to 31ms on the 42LM660, with our best solution being to label the necessary HDMI input as “PC” and then selecting the “ISF Expert1” mode. This combination allows for this speedy response time, WITH full 4:4:4 chroma detail reproduction. Just be sure that [TruMotion], [Noise Reduction] and other features are disabled to avoid lag.
Conclusion
The LG 42LM660T is a great, no-nonsense example of an LED-lit LCD television using an IPS panel. It has all of the positives and negatives that normally come attached to IPS LCD technology: mediocre black levels, but motion clarity, off-axis viewing angle quality, and linear, largely tint-free images that are all excellent by LCD TV standards.
One thing that makes us look very favourably on the LM660T is the fact that the limitations it does have are inherent to the use of the panel technology used (IPS LCD). In other words, there are no “human errors” that could be avoided, such as forced noise reduction processing (something we wish Samsung would pay attention to, and something we wish LG would keep in mind for its more expensive models). The 42LM660T’s down sides are really just inevitabilities which result from the technology used. The enthusiast user is given a great amount of control over the image, with full calibration menus allowing the panel to be pushed to its limits, and even without calibration, the LG produced a very watchable image. The Korean manufacturer’s Smart TV interface is also very slick, and the inclusion of the Magic Remote makes it very easy to use.
If you’re into 3D, it’s a similar story: the 42LM660T can’t escape the resolution limitation (or the visible black lines over the tri-dimensional image) imposed by the use of passive 3D, but the use of this 3-D method brings many other benefits for fans of extra-dimensional content. Neither the active or passive 3D systems are for everyone, with the choice of which set of strengths and weaknesses to adopt down to the individual. We would like to see the slight pixellation issues with side-by-side 3D content addressed, though.
Certain plasma TVs may perform better in terms of picture quality, but they’re not suitable for all viewing environments, and some people prefer the traits found on LCD panels to those found on plasmas, meaning that displays such as the LM660T are not without an audience. If IPS LCD is right for your viewing habits and you have no use for 100hz/200hz motion interpolation features, then the LG 42LM660T stands as a brilliant, no-nonsense example, and the fact that it’s brilliantly styled doesn’t hurt, either.
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