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LG 55LH90

Product Description

Earlier this week I got together with Chris from Cleveland Plasma to review the new, local dimming LED backlight 55LH90 LCD. This was my first experience with an LG LCD TV; I have calibrated several of their plasmas and one of their slim direct view CRT sets in the past. None of those past sets have left a favorable impression, but I was eager to see if the THX and ISF influence, along with the local dimming LEDs, were signs that LG was on the right track. I had calibrated the first generation (81 series) Samsung and Sony XBR8 local dimming sets in the past, and they had some very exciting strong points.

First off, I think LG should be congratulated for not using a glossy screen. I was very impressed with how well the screen muted reflections in a moderately bright room. I hate watching myself watch TV, and thankfully the LG doesn't try to make me. ;) With both sets turned off, it's screen looked darker than the Samsung B550 that was next to it.

I also wanted to check how well the color and contrast held up off to the sides, and the LG did better in that regard than the other LCD's I've done recently. I had to be at pretty extreme angles before the picture lost contrast or color. Very nice. Interestingly, at those extreme angles, I could see glowing around bright objects; most likely a side effect of the local dimming. However, that glowing was not visible at normal angles.

I started by measuring the LG's performance out of the box in several different modes. As is often the case with dynamic backlights, I got different light output levels from small and large windows and full fields; the difference is exactly opposite that of a plasma, with the full field being slightly brighter than a small window. However, the difference was not nearly as pronounced as that of the Samsung B7100, for example. I split the difference and used large windows. The first 4 attachments are the results for standard, natural, ISF, and THX modes. The ISF and THX modes looked pretty good except for being way too dim in a normal room, but there's still room for improvement even without taking the low light output into account.

I was amazed at how extensive the adjustments were in the ISF mode. These adjustments are open to anyone, no code or special software needed. However, you do need the proper tools to calibrate them correctly. I was happy and surprised to see a 10 step grayscale adjustment option. This works just like the 11 step adjustment in the Lumagen video processors, and it even has the same slightly quirky/picky behavior. However, with patience it can make an amazing difference in the measured grayscale and gamma. This can help the image to look more natural with a greater sense of depth.

There is a selection for color gamut and for turning the local dimming on and off. There is also color isolation in ISF mode, though I found I had to cycle the color gamut selection when using it or it wouldn't work correctly. ISF mode includes a full CMS adjustment that works properly and allows adjustment of the level and hue of each primary and secondary color.

There are separate horizontal and vertical sharpness controls, and edge enhancement has no effect in ISF mode. There is a Just Scan size mode which offers pixel perfect resolution at 1080i or 1080P. The 240 Hz motion control was on low by default in ISF mode, and that's where I left it for the viewing. Pans were generally super smooth (maybe too smooth), though I did notice a brief blurring effect when someone's head was quickly panned across the screen. I also thought I noticed a few very brief moments of jagginess. Neither was enough to bother me; they barely registered with me, though I wasn't specifically looking for them. I suppose if I was fixated on that aspect of the performance they could come in to play more. Also, faster moving images might make it more apparent.

The backlight strength adjustment had no significant effect on the calibration other than light output, so you could use it to adjust to different lighting situations. With it turned up, this TV can be a light cannon, with calibrated light output capability ranging from 30 to over 90 fL. That adjustment combined with the non glare screen make it a perfect set for either a bright living room or a dark theater.

I did not have a meter that was trustworthy with ultra low light measurements on an LCD display, so all I could get is a general idea of the contrast ratio with local dimming on. The contrast ratio was extremely high, with super dark blacks. The local dimming seemed to work very, very well with no visible pumping with regular material (the brightness test pattern on the AVS Blu Ray DVD did show some pumping, but you'll understand why if you see it) and no glowing around bright objects except at extreme off axis angles.

With local dimming off, on/off contrast ratio was around 700-1100:1, which is pretty typical for a good fixed backlight LCD. However, I would not use it that way if I owned it. The local dimming improves the contrast so dramatically with so few side effects I can't see any reason not to use it.

Though the room was moderately bright, I did drape a black velvet blanket over the set while peeking my head in between to evaluate the blacks and near black performance. This resulted in a makeshift dark tent around the set.

The calibration took much longer than usual because of the CMS adjustment and the 10 step grayscale adjustment, which I decided to use instead of the 2 step. It is not an adjustment you can do if you are in a hurry, but it's well worth it. The results are shown in the last attachment. Color decoding, color gamut, grayscale, and gamma are all very good to superb. Contrast ratio looked superb, though the room was not dark enough to see the full extent of it.

One slight flaw that did not show up in the measurements is the set's performance just coming out of black. If I set the brightness (black level) so the background was as black as it could be, the blacks were slightly crushed. This was most noticeable with the AVS Blu Ray test DVD's brightness pattern. If I set the brightness so the blacks were not crushed at all, the blacks were not quite as dark. I decided to set it for the blackest blacks and live with a little bit of black crush at 1-3% or so.

The resulting image was very impressive! After making a final color tweek, I appreciated the high light output, super accurate colors, and great contrast. Faces looked rich without looking sunburnt. It was time to go head to head with a Samsung B550 I calibrated recently. I felt the LG looked slightly less "enhanced" and less colored (that may be due to the B550's slightly too wide color gamut). The higher light output and smoother pans were noticeable. The LG had more contrast in dark scenes. But overall, the B550 being the good plasma that it is, there was not as much difference as I had expected.

This is a TV that, if you don't like it, it probably has more to do with the adjustments not being calibrated as well as they could be than with any shortcoming of the set. It is that good. :D

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